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[PATCH v1] WIP: Support for extended information about signals
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* [PATCH v1] WIP: Support for extended information about signals
@ 2026-04-08 16:43 Andres Freund <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Andres Freund @ 2026-04-08 16:43 UTC (permalink / raw)

Author:
Reviewed-by:
Discussion: https://postgr.es/m/
Backpatch-through:
---
 src/include/c.h                             | 27 +++++---
 src/include/port.h                          |  3 +
 src/port/pqsignal.c                         | 76 ++++++++++++++-------
 src/backend/bootstrap/bootstrap.c           |  8 +--
 src/backend/postmaster/autovacuum.c         | 10 +--
 src/backend/postmaster/bgworker.c           | 14 ++--
 src/backend/postmaster/bgwriter.c           | 10 +--
 src/backend/postmaster/checkpointer.c       |  8 +--
 src/backend/postmaster/datachecksum_state.c |  2 +-
 src/backend/postmaster/pgarch.c             |  8 +--
 src/backend/postmaster/postmaster.c         | 12 ++--
 src/backend/postmaster/startup.c            |  6 +-
 src/backend/postmaster/syslogger.c          | 14 ++--
 src/backend/postmaster/walsummarizer.c      | 10 +--
 src/backend/postmaster/walwriter.c          | 10 +--
 src/backend/replication/logical/slotsync.c  |  6 +-
 src/backend/replication/walreceiver.c       | 10 +--
 src/backend/replication/walsender.c         |  4 +-
 src/backend/storage/aio/method_worker.c     |  6 +-
 src/backend/storage/file/fd.c               |  4 +-
 src/backend/storage/ipc/waiteventset.c      |  2 +-
 src/backend/tcop/postgres.c                 | 17 +++--
 src/fe_utils/print.c                        |  4 +-
 src/bin/initdb/initdb.c                     |  4 +-
 src/bin/pg_ctl/pg_ctl.c                     |  2 +-
 src/bin/pg_dump/parallel.c                  |  8 +--
 src/interfaces/libpq/legacy-pqsignal.c      |  8 ++-
 src/test/regress/pg_regress.c               |  2 +-
 src/tools/pgindent/typedefs.list            |  1 +
 29 files changed, 174 insertions(+), 122 deletions(-)

diff --git a/src/include/c.h b/src/include/c.h
index 88d13ec9993..77ea73cc707 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -1441,17 +1441,26 @@ extern int	fdatasync(int fd);
 #endif
 
 /*
- * The following is used as the arg list for signal handlers.  Any ports
- * that take something other than an int argument should override this in
- * their pg_config_os.h file.  Note that variable names are required
- * because it is used in both the prototypes as well as the definitions.
- * Note also the long name.  We expect that this won't collide with
- * other names causing compiler warnings.
+ * Platform independent struct representing additional information about the
+ * received signal.  If the system does not support the extended information,
+ * or a field does not apply to the signal, the value is instead reset to the
+ * documented default value.
  */
+typedef struct pg_signal_info
+{
+	pid_t		pid;			/* pid of sending process or 0 if unknown */
+	uid_t		uid;			/* uid of sending process or 0 if unknown */
+} pg_signal_info;
 
-#ifndef SIGNAL_ARGS
-#define SIGNAL_ARGS  int postgres_signal_arg
-#endif
+/*
+ * The following is used as the arg list for signal handlers. These days we
+ * use the same argument to all signal handlers and hide the difference
+ * between platforms in wrapper functions.
+ *
+ * SIGNAL_ARGS just exists separately from the pqsignal() definition for
+ * historical reasons.
+ */
+#define SIGNAL_ARGS  int postgres_signal_arg, pg_signal_info *pg_siginfo
 
 /*
  * When there is no sigsetjmp, its functionality is provided by plain
diff --git a/src/include/port.h b/src/include/port.h
index 51df9b80e7d..7db476d7b01 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -546,6 +546,9 @@ extern int	pg_mkdir_p(char *path, int omode);
 #else
 #define pqsignal pqsignal_be
 #endif
+
+#define PG_SIG_DFL (pqsigfunc) SIG_DFL
+#define PG_SIG_IGN (pqsigfunc) SIG_IGN
 typedef void (*pqsigfunc) (SIGNAL_ARGS);
 extern void pqsignal(int signo, pqsigfunc func);
 
diff --git a/src/port/pqsignal.c b/src/port/pqsignal.c
index 8841464b5cb..a5b32ec3945 100644
--- a/src/port/pqsignal.c
+++ b/src/port/pqsignal.c
@@ -63,6 +63,15 @@
 #define PG_NSIG (64)			/* XXX: wild guess */
 #endif
 
+#if !(defined(WIN32) && defined(FRONTEND))
+#define USE_SIGACTION
+#endif
+
+#if defined(USE_SIGACTION) && defined(HAVE_SA_SIGINFO)
+#define USE_SIGINFO
+#endif
+
+
 /* Check a couple of common signals to make sure PG_NSIG is accurate. */
 StaticAssertDecl(SIGUSR2 < PG_NSIG, "SIGUSR2 >= PG_NSIG");
 StaticAssertDecl(SIGHUP < PG_NSIG, "SIGHUP >= PG_NSIG");
@@ -82,19 +91,16 @@ static volatile pqsigfunc pqsignal_handlers[PG_NSIG];
  *
  * This wrapper also handles restoring the value of errno.
  */
-#if !defined(FRONTEND) && defined(HAVE_SA_SIGINFO)
+#ifdef USE_SIGACTION
 static void
-wrapper_handler(int signo, siginfo_t * info, void *context)
+wrapper_handler(int postgres_signal_arg, siginfo_t * info, void *context)
 #else
 static void
-wrapper_handler(SIGNAL_ARGS)
+wrapper_handler(int postgres_signal_arg)
 #endif
 {
 	int			save_errno = errno;
-#if !defined(FRONTEND) && defined(HAVE_SA_SIGINFO)
-	/* SA_SIGINFO signature uses signo, not SIGNAL_ARGS macro */
-	int			postgres_signal_arg = signo;
-#endif
+	pg_signal_info pg_info;
 
 	Assert(postgres_signal_arg > 0);
 	Assert(postgres_signal_arg < PG_NSIG);
@@ -110,21 +116,32 @@ wrapper_handler(SIGNAL_ARGS)
 
 	if (unlikely(MyProcPid != (int) getpid()))
 	{
-		pqsignal(postgres_signal_arg, SIG_DFL);
+		pqsignal(postgres_signal_arg, PG_SIG_DFL);
 		raise(postgres_signal_arg);
 		return;
 	}
+#endif
 
 #ifdef HAVE_SA_SIGINFO
-	if (signo == SIGTERM && info)
-	{
-		ProcDieSenderPid = info->si_pid;
-		ProcDieSenderUid = info->si_uid;
-	}
-#endif
+
+	/*
+	 * If supported by the system, forward interesting information from the
+	 * system's extended signal information to our platform independent
+	 * format.
+	 */
+	pg_info.pid = info->si_pid;
+	pg_info.uid = info->si_uid;
+#else
+
+	/*
+	 * Otherwise forward values indicating that we do not have the
+	 * information.
+	 */
+	pg_info.pid = 0;
+	pg_info.uid = 0;
 #endif
 
-	(*pqsignal_handlers[postgres_signal_arg]) (postgres_signal_arg);
+	(*pqsignal_handlers[postgres_signal_arg]) (postgres_signal_arg, &pg_info);
 
 	errno = save_errno;
 }
@@ -139,33 +156,44 @@ wrapper_handler(SIGNAL_ARGS)
 void
 pqsignal(int signo, pqsigfunc func)
 {
-#if !(defined(WIN32) && defined(FRONTEND))
+#ifdef USE_SIGACTION
 	struct sigaction act;
 #endif
-	bool		use_wrapper = false;
+	bool		is_ign = func == PG_SIG_IGN;
+	bool		is_dfl = func == PG_SIG_DFL;
 
 	Assert(signo > 0);
 	Assert(signo < PG_NSIG);
 
-	if (func != SIG_IGN && func != SIG_DFL)
+	/* set up indirection handler */
+	if (!(is_ign || is_dfl))
 	{
 		pqsignal_handlers[signo] = func;	/* assumed atomic */
-		use_wrapper = true;
 	}
 
-#if !(defined(WIN32) && defined(FRONTEND))
+	/*
+	 * Configure system to either ignore/reset the signal handler, or to
+	 * forward it to wrapper_handler.
+	 */
+#ifdef USE_SIGACTION
 	sigemptyset(&act.sa_mask);
 	act.sa_flags = SA_RESTART;
-#if !defined(FRONTEND) && defined(HAVE_SA_SIGINFO)
-	if (use_wrapper)
+
+	if (is_ign)
+		act.sa_handler = SIG_IGN;
+	else if (is_dfl)
+		act.sa_handler = SIG_DFL;
+
+#ifdef USE_SIGINFO
+	if (!(is_ign || is_dfl))
 	{
 		act.sa_sigaction = wrapper_handler;
 		act.sa_flags |= SA_SIGINFO;
 	}
 	else
-		act.sa_handler = func;
 #else
-	act.sa_handler = use_wrapper ? wrapper_handler : func;
+	else
+		act.sa_handler = wrapper_handler;
 #endif
 
 #ifdef SA_NOCLDSTOP
diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index a4af7bf8fad..b0dcd9876c5 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -463,10 +463,10 @@ bootstrap_signals(void)
 	 * mode; "curl up and die" is a sufficient response for all these cases.
 	 * Let's set that handling explicitly, as documentation if nothing else.
 	 */
-	pqsignal(SIGHUP, SIG_DFL);
-	pqsignal(SIGINT, SIG_DFL);
-	pqsignal(SIGTERM, SIG_DFL);
-	pqsignal(SIGQUIT, SIG_DFL);
+	pqsignal(SIGHUP, PG_SIG_DFL);
+	pqsignal(SIGINT, PG_SIG_DFL);
+	pqsignal(SIGTERM, PG_SIG_DFL);
+	pqsignal(SIGQUIT, PG_SIG_DFL);
 }
 
 /* ----------------------------------------------------------------
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index bd626a16363..2a87d26aa6f 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -445,11 +445,11 @@ AutoVacLauncherMain(const void *startup_data, size_t startup_data_len)
 
 	InitializeTimeouts();		/* establishes SIGALRM handler */
 
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
 	pqsignal(SIGUSR2, avl_sigusr2_handler);
 	pqsignal(SIGFPE, FloatExceptionHandler);
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 
 	/*
 	 * Create a per-backend PGPROC struct in shared memory.  We must do this
@@ -1456,11 +1456,11 @@ AutoVacWorkerMain(const void *startup_data, size_t startup_data_len)
 
 	InitializeTimeouts();		/* establishes SIGALRM handler */
 
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
-	pqsignal(SIGUSR2, SIG_IGN);
+	pqsignal(SIGUSR2, PG_SIG_IGN);
 	pqsignal(SIGFPE, FloatExceptionHandler);
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 
 	/*
 	 * Create a per-backend PGPROC struct in shared memory.  We must do this
diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c
index 3914d22a514..2e4acad4f00 100644
--- a/src/backend/postmaster/bgworker.c
+++ b/src/backend/postmaster/bgworker.c
@@ -785,19 +785,19 @@ BackgroundWorkerMain(const void *startup_data, size_t startup_data_len)
 	}
 	else
 	{
-		pqsignal(SIGINT, SIG_IGN);
-		pqsignal(SIGUSR1, SIG_IGN);
-		pqsignal(SIGFPE, SIG_IGN);
+		pqsignal(SIGINT, PG_SIG_IGN);
+		pqsignal(SIGUSR1, PG_SIG_IGN);
+		pqsignal(SIGFPE, PG_SIG_IGN);
 	}
 	pqsignal(SIGTERM, die);
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGHUP, SIG_IGN);
+	pqsignal(SIGHUP, PG_SIG_IGN);
 
 	InitializeTimeouts();		/* establishes SIGALRM handler */
 
-	pqsignal(SIGPIPE, SIG_IGN);
-	pqsignal(SIGUSR2, SIG_IGN);
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
+	pqsignal(SIGUSR2, PG_SIG_IGN);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 
 	/*
 	 * If an exception is encountered, processing resumes here.
diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c
index a30de4262eb..cd1bf9d919c 100644
--- a/src/backend/postmaster/bgwriter.c
+++ b/src/backend/postmaster/bgwriter.c
@@ -101,18 +101,18 @@ BackgroundWriterMain(const void *startup_data, size_t startup_data_len)
 	 * Properly accept or ignore signals that might be sent to us.
 	 */
 	pqsignal(SIGHUP, SignalHandlerForConfigReload);
-	pqsignal(SIGINT, SIG_IGN);
+	pqsignal(SIGINT, PG_SIG_IGN);
 	pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGALRM, SIG_IGN);
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGALRM, PG_SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
-	pqsignal(SIGUSR2, SIG_IGN);
+	pqsignal(SIGUSR2, PG_SIG_IGN);
 
 	/*
 	 * Reset some signals that are accepted by postmaster but not here
 	 */
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 
 	/*
 	 * We just started, assume there has been either a shutdown or
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index 6b424ee610f..087120db090 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -223,17 +223,17 @@ CheckpointerMain(const void *startup_data, size_t startup_data_len)
 	 */
 	pqsignal(SIGHUP, SignalHandlerForConfigReload);
 	pqsignal(SIGINT, ReqShutdownXLOG);
-	pqsignal(SIGTERM, SIG_IGN); /* ignore SIGTERM */
+	pqsignal(SIGTERM, PG_SIG_IGN);	/* ignore SIGTERM */
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGALRM, SIG_IGN);
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGALRM, PG_SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
 	pqsignal(SIGUSR2, SignalHandlerForShutdownRequest);
 
 	/*
 	 * Reset some signals that are accepted by postmaster but not here
 	 */
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 
 	/*
 	 * Initialize so that first time-driven event happens at the correct time.
diff --git a/src/backend/postmaster/datachecksum_state.c b/src/backend/postmaster/datachecksum_state.c
index 1243949eacb..18797a8ee3d 100644
--- a/src/backend/postmaster/datachecksum_state.c
+++ b/src/backend/postmaster/datachecksum_state.c
@@ -1020,7 +1020,7 @@ DataChecksumsWorkerLauncherMain(Datum arg)
 	pqsignal(SIGTERM, die);
 	pqsignal(SIGINT, launcher_cancel_handler);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
-	pqsignal(SIGUSR2, SIG_IGN);
+	pqsignal(SIGUSR2, PG_SIG_IGN);
 
 	BackgroundWorkerUnblockSignals();
 
diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
index 0a1a1149d78..0f207ac0356 100644
--- a/src/backend/postmaster/pgarch.c
+++ b/src/backend/postmaster/pgarch.c
@@ -229,16 +229,16 @@ PgArchiverMain(const void *startup_data, size_t startup_data_len)
 	 * except for SIGHUP, SIGTERM, SIGUSR1, SIGUSR2, and SIGQUIT.
 	 */
 	pqsignal(SIGHUP, SignalHandlerForConfigReload);
-	pqsignal(SIGINT, SIG_IGN);
+	pqsignal(SIGINT, PG_SIG_IGN);
 	pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGALRM, SIG_IGN);
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGALRM, PG_SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
 	pqsignal(SIGUSR2, pgarch_waken_stop);
 
 	/* Reset some signals that are accepted by postmaster but not here */
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 
 	/* Unblock signals (they were blocked when the postmaster forked us) */
 	sigprocmask(SIG_SETMASK, &UnBlockSig, NULL);
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 6e0f41d2661..b6fd332f196 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -555,8 +555,8 @@ PostmasterMain(int argc, char *argv[])
 	pqsignal(SIGINT, handle_pm_shutdown_request_signal);
 	pqsignal(SIGQUIT, handle_pm_shutdown_request_signal);
 	pqsignal(SIGTERM, handle_pm_shutdown_request_signal);
-	pqsignal(SIGALRM, SIG_IGN); /* ignored */
-	pqsignal(SIGPIPE, SIG_IGN); /* ignored */
+	pqsignal(SIGALRM, PG_SIG_IGN);	/* ignored */
+	pqsignal(SIGPIPE, PG_SIG_IGN);	/* ignored */
 	pqsignal(SIGUSR1, handle_pm_pmsignal_signal);
 	pqsignal(SIGUSR2, dummy_handler);	/* unused, reserve for children */
 	pqsignal(SIGCHLD, handle_pm_child_exit_signal);
@@ -573,15 +573,15 @@ PostmasterMain(int argc, char *argv[])
 	 * child processes should just allow the inherited settings to stand.
 	 */
 #ifdef SIGTTIN
-	pqsignal(SIGTTIN, SIG_IGN); /* ignored */
+	pqsignal(SIGTTIN, PG_SIG_IGN);	/* ignored */
 #endif
 #ifdef SIGTTOU
-	pqsignal(SIGTTOU, SIG_IGN); /* ignored */
+	pqsignal(SIGTTOU, PG_SIG_IGN);	/* ignored */
 #endif
 
 	/* ignore SIGXFSZ, so that ulimit violations work like disk full */
 #ifdef SIGXFSZ
-	pqsignal(SIGXFSZ, SIG_IGN); /* ignored */
+	pqsignal(SIGXFSZ, PG_SIG_IGN);	/* ignored */
 #endif
 
 	/* Begin accepting signals. */
@@ -3967,7 +3967,7 @@ process_pm_pmsignal(void)
  * Dummy signal handler
  *
  * We use this for signals that we don't actually use in the postmaster,
- * but we do use in backends.  If we were to SIG_IGN such signals in the
+ * but we do use in backends.  If we were to PG_SIG_IGN such signals in the
  * postmaster, then a newly started backend might drop a signal that arrives
  * before it's able to reconfigure its signal processing.  (See notes in
  * tcop/postgres.c.)
diff --git a/src/backend/postmaster/startup.c b/src/backend/postmaster/startup.c
index cdbe53dd262..b46bac681fe 100644
--- a/src/backend/postmaster/startup.c
+++ b/src/backend/postmaster/startup.c
@@ -226,18 +226,18 @@ StartupProcessMain(const void *startup_data, size_t startup_data_len)
 	 * Properly accept or ignore signals the postmaster might send us.
 	 */
 	pqsignal(SIGHUP, StartupProcSigHupHandler); /* reload config file */
-	pqsignal(SIGINT, SIG_IGN);	/* ignore query cancel */
+	pqsignal(SIGINT, PG_SIG_IGN);	/* ignore query cancel */
 	pqsignal(SIGTERM, StartupProcShutdownHandler);	/* request shutdown */
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
 	InitializeTimeouts();		/* establishes SIGALRM handler */
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
 	pqsignal(SIGUSR2, StartupProcTriggerHandler);
 
 	/*
 	 * Reset some signals that are accepted by postmaster but not here
 	 */
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 
 	/*
 	 * Register timeouts needed for standby mode
diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
index 0c2a7bc8578..acfe0a01715 100644
--- a/src/backend/postmaster/syslogger.c
+++ b/src/backend/postmaster/syslogger.c
@@ -276,18 +276,18 @@ SysLoggerMain(const void *startup_data, size_t startup_data_len)
 
 	pqsignal(SIGHUP, SignalHandlerForConfigReload); /* set flag to read config
 													 * file */
-	pqsignal(SIGINT, SIG_IGN);
-	pqsignal(SIGTERM, SIG_IGN);
-	pqsignal(SIGQUIT, SIG_IGN);
-	pqsignal(SIGALRM, SIG_IGN);
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGINT, PG_SIG_IGN);
+	pqsignal(SIGTERM, PG_SIG_IGN);
+	pqsignal(SIGQUIT, PG_SIG_IGN);
+	pqsignal(SIGALRM, PG_SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	pqsignal(SIGUSR1, sigUsr1Handler);	/* request log rotation */
-	pqsignal(SIGUSR2, SIG_IGN);
+	pqsignal(SIGUSR2, PG_SIG_IGN);
 
 	/*
 	 * Reset some signals that are accepted by postmaster but not here
 	 */
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 
 	sigprocmask(SIG_SETMASK, &UnBlockSig, NULL);
 
diff --git a/src/backend/postmaster/walsummarizer.c b/src/backend/postmaster/walsummarizer.c
index 20960f5b633..4f12eaf2c85 100644
--- a/src/backend/postmaster/walsummarizer.c
+++ b/src/backend/postmaster/walsummarizer.c
@@ -244,13 +244,13 @@ WalSummarizerMain(const void *startup_data, size_t startup_data_len)
 	 * Properly accept or ignore signals the postmaster might send us
 	 */
 	pqsignal(SIGHUP, SignalHandlerForConfigReload);
-	pqsignal(SIGINT, SIG_IGN);	/* no query to cancel */
+	pqsignal(SIGINT, PG_SIG_IGN);	/* no query to cancel */
 	pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGALRM, SIG_IGN);
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGALRM, PG_SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
-	pqsignal(SIGUSR2, SIG_IGN); /* not used */
+	pqsignal(SIGUSR2, PG_SIG_IGN);	/* not used */
 
 	/* Advertise ourselves. */
 	on_shmem_exit(WalSummarizerShutdown, (Datum) 0);
@@ -267,7 +267,7 @@ WalSummarizerMain(const void *startup_data, size_t startup_data_len)
 	/*
 	 * Reset some signals that are accepted by postmaster but not here
 	 */
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 
 	/*
 	 * If an exception is encountered, processing resumes here.
diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index 9cd86ad7022..af24d05c542 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -101,18 +101,18 @@ WalWriterMain(const void *startup_data, size_t startup_data_len)
 	 * Properly accept or ignore signals the postmaster might send us
 	 */
 	pqsignal(SIGHUP, SignalHandlerForConfigReload);
-	pqsignal(SIGINT, SIG_IGN);	/* no query to cancel */
+	pqsignal(SIGINT, PG_SIG_IGN);	/* no query to cancel */
 	pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGALRM, SIG_IGN);
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGALRM, PG_SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
-	pqsignal(SIGUSR2, SIG_IGN); /* not used */
+	pqsignal(SIGUSR2, PG_SIG_IGN);	/* not used */
 
 	/*
 	 * Reset some signals that are accepted by postmaster but not here
 	 */
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 
 	/*
 	 * Create a memory context that we will do all our work in.  We do this so
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index f90653e5232..354e16c9d33 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -1608,9 +1608,9 @@ ReplSlotSyncWorkerMain(const void *startup_data, size_t startup_data_len)
 	pqsignal(SIGTERM, die);
 	pqsignal(SIGFPE, FloatExceptionHandler);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
-	pqsignal(SIGUSR2, SIG_IGN);
-	pqsignal(SIGPIPE, SIG_IGN);
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGUSR2, PG_SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 
 	check_and_set_sync_info(MyProcPid);
 
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 09fde92bfd7..6da5b86dbc5 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -248,16 +248,16 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 	/* Properly accept or ignore signals the postmaster might send us */
 	pqsignal(SIGHUP, SignalHandlerForConfigReload); /* set flag to read config
 													 * file */
-	pqsignal(SIGINT, SIG_IGN);
+	pqsignal(SIGINT, PG_SIG_IGN);
 	pqsignal(SIGTERM, die);		/* request shutdown */
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGALRM, SIG_IGN);
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGALRM, PG_SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
-	pqsignal(SIGUSR2, SIG_IGN);
+	pqsignal(SIGUSR2, PG_SIG_IGN);
 
 	/* Reset some signals that are accepted by postmaster but not here */
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 
 	/* Load the libpq-specific functions */
 	load_file("libpqwalreceiver", false);
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index bad45adb004..3d4ab929f91 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -3897,13 +3897,13 @@ WalSndSignals(void)
 	pqsignal(SIGTERM, die);		/* request shutdown */
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
 	InitializeTimeouts();		/* establishes SIGALRM handler */
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
 	pqsignal(SIGUSR2, WalSndLastCycleHandler);	/* request a last cycle and
 												 * shutdown */
 
 	/* Reset some signals that are accepted by postmaster but not here */
-	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGCHLD, PG_SIG_DFL);
 }
 
 /* Register shared-memory space needed by walsender */
diff --git a/src/backend/storage/aio/method_worker.c b/src/backend/storage/aio/method_worker.c
index a5ccd506d8c..061a93d90d4 100644
--- a/src/backend/storage/aio/method_worker.c
+++ b/src/backend/storage/aio/method_worker.c
@@ -684,10 +684,10 @@ IoWorkerMain(const void *startup_data, size_t startup_data_len)
 	 * Ignore SIGTERM, will get explicit shutdown via SIGUSR2 later in the
 	 * shutdown sequence, similar to checkpointer.
 	 */
-	pqsignal(SIGTERM, SIG_IGN);
+	pqsignal(SIGTERM, PG_SIG_IGN);
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGALRM, SIG_IGN);
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGALRM, PG_SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
 	pqsignal(SIGUSR2, SignalHandlerForShutdownRequest);
 
diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index 01f1bd6e687..a8be066afe0 100644
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -2748,11 +2748,11 @@ OpenPipeStream(const char *command, const char *mode)
 
 TryAgain:
 	fflush(NULL);
-	pqsignal(SIGPIPE, SIG_DFL);
+	pqsignal(SIGPIPE, PG_SIG_DFL);
 	errno = 0;
 	file = popen(command, mode);
 	save_errno = errno;
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 	errno = save_errno;
 	if (file != NULL)
 	{
diff --git a/src/backend/storage/ipc/waiteventset.c b/src/backend/storage/ipc/waiteventset.c
index 0f228e1e7b8..627dba0a842 100644
--- a/src/backend/storage/ipc/waiteventset.c
+++ b/src/backend/storage/ipc/waiteventset.c
@@ -348,7 +348,7 @@ InitializeWaitEventSupport(void)
 
 #ifdef WAIT_USE_KQUEUE
 	/* Ignore SIGURG, because we'll receive it via kqueue. */
-	pqsignal(SIGURG, SIG_IGN);
+	pqsignal(SIGURG, PG_SIG_IGN);
 #endif
 }
 
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index aeaf1c6db8f..9df6bc4e01b 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -3029,6 +3029,15 @@ die(SIGNAL_ARGS)
 		ProcDiePending = true;
 	}
 
+	/*
+	 * Will be 0 if unsupported by the system, but that suits us just fine.
+	 *
+	 * XXX: Seems we only should set these if not already set? We'd probably
+	 * want to know the first signal.
+	 */
+	ProcDieSenderPid = pg_siginfo->pid;
+	ProcDieSenderUid = pg_siginfo->uid;
+
 	/* for the cumulative stats system */
 	pgStatSessionEndCause = DISCONNECT_KILLED;
 
@@ -4316,17 +4325,17 @@ PostgresMain(const char *dbname, const char *username)
 		 * returns to outer loop.  This seems safer than forcing exit in the
 		 * midst of output during who-knows-what operation...
 		 */
-		pqsignal(SIGPIPE, SIG_IGN);
+		pqsignal(SIGPIPE, PG_SIG_IGN);
 		pqsignal(SIGUSR1, procsignal_sigusr1_handler);
-		pqsignal(SIGUSR2, SIG_IGN);
+		pqsignal(SIGUSR2, PG_SIG_IGN);
 		pqsignal(SIGFPE, FloatExceptionHandler);
 
 		/*
 		 * Reset some signals that are accepted by postmaster but not by
 		 * backend
 		 */
-		pqsignal(SIGCHLD, SIG_DFL); /* system() requires this on some
-									 * platforms */
+		pqsignal(SIGCHLD, PG_SIG_DFL);	/* system() requires this on some
+										 * platforms */
 	}
 
 	/* Early initialization */
diff --git a/src/fe_utils/print.c b/src/fe_utils/print.c
index 12d969e8666..f2dd52003c1 100644
--- a/src/fe_utils/print.c
+++ b/src/fe_utils/print.c
@@ -3024,7 +3024,7 @@ void
 disable_sigpipe_trap(void)
 {
 #ifndef WIN32
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 #endif
 }
 
@@ -3047,7 +3047,7 @@ void
 restore_sigpipe_trap(void)
 {
 #ifndef WIN32
-	pqsignal(SIGPIPE, always_ignore_sigpipe ? SIG_IGN : SIG_DFL);
+	pqsignal(SIGPIPE, always_ignore_sigpipe ? PG_SIG_IGN : PG_SIG_DFL);
 #endif
 }
 
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 509f1114ef6..44a2c7a7c7f 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -2903,10 +2903,10 @@ setup_signals(void)
 	pqsignal(SIGQUIT, trapsig);
 
 	/* Ignore SIGPIPE when writing to backend, so we can clean up */
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 
 	/* Prevent SIGSYS so we can probe for kernel calls that might not work */
-	pqsignal(SIGSYS, SIG_IGN);
+	pqsignal(SIGSYS, PG_SIG_IGN);
 #endif
 }
 
diff --git a/src/bin/pg_ctl/pg_ctl.c b/src/bin/pg_ctl/pg_ctl.c
index 3cc61455dcb..5539eb8ebef 100644
--- a/src/bin/pg_ctl/pg_ctl.c
+++ b/src/bin/pg_ctl/pg_ctl.c
@@ -868,7 +868,7 @@ trap_sigint_during_startup(SIGNAL_ARGS)
 	 * Clear the signal handler, and send the signal again, to terminate the
 	 * process as normal.
 	 */
-	pqsignal(postgres_signal_arg, SIG_DFL);
+	pqsignal(postgres_signal_arg, PG_SIG_DFL);
 	raise(postgres_signal_arg);
 }
 
diff --git a/src/bin/pg_dump/parallel.c b/src/bin/pg_dump/parallel.c
index a28561fbd84..a7bed5ecccf 100644
--- a/src/bin/pg_dump/parallel.c
+++ b/src/bin/pg_dump/parallel.c
@@ -568,9 +568,9 @@ sigTermHandler(SIGNAL_ARGS)
 	 * signal handler.  That could muck up our attempt to send PQcancel, so
 	 * disable the signals that set_cancel_handler enabled.
 	 */
-	pqsignal(SIGINT, SIG_IGN);
-	pqsignal(SIGTERM, SIG_IGN);
-	pqsignal(SIGQUIT, SIG_IGN);
+	pqsignal(SIGINT, PG_SIG_IGN);
+	pqsignal(SIGTERM, PG_SIG_IGN);
+	pqsignal(SIGQUIT, PG_SIG_IGN);
 
 	/*
 	 * If we're in the leader, forward signal to all workers.  (It seems best
@@ -1049,7 +1049,7 @@ ParallelBackupStart(ArchiveHandle *AH)
 	 * the workers to inherit this setting, though.
 	 */
 #ifndef WIN32
-	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGPIPE, PG_SIG_IGN);
 #endif
 
 	/*
diff --git a/src/interfaces/libpq/legacy-pqsignal.c b/src/interfaces/libpq/legacy-pqsignal.c
index 1285b033e1b..0735e4ee0d5 100644
--- a/src/interfaces/libpq/legacy-pqsignal.c
+++ b/src/interfaces/libpq/legacy-pqsignal.c
@@ -36,10 +36,12 @@
  * is to ensure that no in-tree code accidentally calls this version.)
  */
 #undef pqsignal
-extern pqsigfunc pqsignal(int signo, pqsigfunc func);
 
-pqsigfunc
-pqsignal(int signo, pqsigfunc func)
+typedef void (*pqsigfunc_legacy) (int postgres_signal_arg);
+extern pqsigfunc_legacy pqsignal(int signo, pqsigfunc_legacy func);
+
+pqsigfunc_legacy
+pqsignal(int signo, pqsigfunc_legacy func)
 {
 #ifndef WIN32
 	struct sigaction act,
diff --git a/src/test/regress/pg_regress.c b/src/test/regress/pg_regress.c
index 0c062056982..c26efeba1ee 100644
--- a/src/test/regress/pg_regress.c
+++ b/src/test/regress/pg_regress.c
@@ -492,7 +492,7 @@ signal_remove_temp(SIGNAL_ARGS)
 {
 	remove_temp();
 
-	pqsignal(postgres_signal_arg, SIG_DFL);
+	pqsignal(postgres_signal_arg, PG_SIG_DFL);
 	raise(postgres_signal_arg);
 }
 
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index ea95e7984bc..49dfb662abc 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -4039,6 +4039,7 @@ pg_sha224_ctx
 pg_sha256_ctx
 pg_sha384_ctx
 pg_sha512_ctx
+pg_signal_info
 pg_snapshot
 pg_special_case
 pg_stack_base_t
-- 
2.53.0.1.gb2826b52eb


--eg7nrzumfkoq4ucj--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v1] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion:
---
 src/backend/utils/activity/pgstat.c       | 45 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 6 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..5180201c4e8 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,15 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1339,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1362,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--jlSGGOUQ0kGWBHE+--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread

* [PATCH v2] Prevent crash when calling pgstat functions with unregistered stats kind
@ 2026-07-01 05:43 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 342+ messages in thread

From: Bertrand Drouvot @ 2026-07-01 05:43 UTC (permalink / raw)

If a custom statistics extension is loaded via CREATE EXTENSION without
being listed in shared_preload_libraries, its _PG_init() skips the call
to pgstat_register_kind(). The SQL functions are still created, and
calling them invokes pgstat functions with a kind that was never registered.

pgstat_get_kind_info() returns NULL in this case. The existing code only
checked this via Assert() in some paths, so non-assert builds would
dereference NULL and segfault.

Add runtime checks in all public-facing pgstat functions that accept a
PgStat_Kind and dereference the returned kind info:

  - pgstat_prep_pending_entry()
  - pgstat_fetch_entry()
  - pgstat_reset()
  - pgstat_reset_of_kind()
  - pgstat_have_entry()
  - pgstat_snapshot_fixed()
  - pgstat_init_entry()
  - pgstat_reset_entry()

Each now raises ERROR with ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE when
the kind is not known or registered.

This affects any extension using the custom cumulative statistics API
introduced in PG18.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by: Ewan Young <[email protected]>
Discussion: https://postgr.es/m/akS/ldidWeqG1FWk%40bdtpg
---
 src/backend/utils/activity/pgstat.c       | 46 ++++++++++++++++++++---
 src/backend/utils/activity/pgstat_shmem.c | 13 ++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)
 100.0% src/backend/utils/activity/

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index c4fa14f138f..540db1ef115 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -885,8 +885,13 @@ pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* not needed atm, and doesn't make sense with the current signature */
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	/* reset the "single counter" */
 	pgstat_reset_entry(kind, dboid, objid, ts);
@@ -907,6 +912,11 @@ pgstat_reset_of_kind(PgStat_Kind kind)
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 	TimestampTz ts = GetCurrentTimestamp();
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	if (kind_info->fixed_amount)
 		kind_info->reset_all_cb(ts);
 	else
@@ -967,6 +977,11 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *may_free)
 	void	   *stats_data;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* should be called from backends */
 	Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
 	Assert(!kind_info->fixed_amount);
@@ -1088,8 +1103,15 @@ pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
 bool
 pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/* fixed-numbered stats always exist */
-	if (pgstat_get_kind_info(kind)->fixed_amount)
+	if (kind_info->fixed_amount)
 		return true;
 
 	return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
@@ -1104,8 +1126,14 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
 void
 pgstat_snapshot_fixed(PgStat_Kind kind)
 {
-	Assert(pgstat_is_kind_valid(kind));
-	Assert(pgstat_get_kind_info(kind)->fixed_amount);
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
+	Assert(kind_info->fixed_amount);
 
 	if (force_stats_snapshot_clear)
 		pgstat_clear_snapshot();
@@ -1310,9 +1338,15 @@ PgStat_EntryRef *
 pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
 	/* need to be able to flush out */
-	Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
+	Assert(kind_info->flush_pending_cb != NULL);
 
 	if (unlikely(!pgStatPendingContext))
 	{
@@ -1327,7 +1361,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index 5ea3f1973f9..4e6a556af93 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -318,6 +318,11 @@ pgstat_init_entry(PgStat_Kind kind,
 	PgStatShared_Common *shheader;
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
+
 	/*
 	 * Initialize refcount to 1, marking it as valid / not dropped. The entry
 	 * can't be freed before the initialization because it can't be found as
@@ -1127,8 +1132,14 @@ void
 pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts)
 {
 	PgStat_EntryRef *entry_ref;
+	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+	if (unlikely(kind_info == NULL))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("statistics kind %u is not known or registered", kind)));
 
-	Assert(!pgstat_get_kind_info(kind)->fixed_amount);
+	Assert(!kind_info->fixed_amount);
 
 	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
 	if (!entry_ref || entry_ref->shared_entry->dropped)
-- 
2.34.1


--cdkC2WBRrpXQO1hi--





^ permalink  raw  reply  [nested|flat] 342+ messages in thread