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[PATCH v46 6/7] Error out any process that would block at REPACK
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* [PATCH v46 6/7] Error out any process that would block at REPACK
@ 2026-03-25 19:35 Álvaro Herrera <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Álvaro Herrera @ 2026-03-25 19:35 UTC (permalink / raw)

Any process waiting on REPACK to release its lock would actually cause
it to deadlock when it tries to upgrade its lock to AEL, losing all work
done to that point.  We avoid this by teaching the deadlock detector to
raise an error when this condition is detected.
---
 src/backend/commands/repack.c                 | 53 ++++++++----
 src/backend/storage/lmgr/deadlock.c           | 15 ++++
 src/include/storage/proc.h                    |  6 +-
 src/test/modules/injection_points/Makefile    |  1 +
 .../expected/repack_deadlock.out              | 63 ++++++++++++++
 src/test/modules/injection_points/meson.build |  1 +
 .../specs/repack_deadlock.spec                | 83 +++++++++++++++++++
 7 files changed, 202 insertions(+), 20 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/repack_deadlock.out
 create mode 100644 src/test/modules/injection_points/specs/repack_deadlock.spec

diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index a58277bb6c1..21ab81c6f7f 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -276,6 +276,16 @@ ExecRepack(ParseState *pstate, RepackStmt *stmt, bool isTopLevel)
 	/* Determine the lock mode to use. */
 	lockmode = RepackLockLevel((params.options & CLUOPT_CONCURRENT) != 0);
 
+	/*
+	 * If in concurrent mode, set the PROC_IN_CONCURRENT_REPACK flag.  This
+	 * makes the deadlock checker cause anyone that would conflict with us
+	 * to error out.  It's important to set this flag ahead of actually locking
+	 * the relation; it won't of course affect anyone until we do have a lock
+	 * that others can conflict with.
+	 */
+	if ((params.options & CLUOPT_CONCURRENT) != 0)
+		MyProc->statusFlags |= PROC_IN_CONCURRENT_REPACK;
+
 	/*
 	 * If a single relation is specified, process it and we're done ... unless
 	 * the relation is a partitioned table, in which case we fall through.
@@ -476,11 +486,8 @@ RepackLockLevel(bool concurrent)
  * If indexOid is InvalidOid, the table will be rewritten in physical order
  * instead of index order.
  *
- * Note that, in the concurrent case, the function releases the lock at some
- * point, in order to get AccessExclusiveLock for the final steps (i.e. to
- * swap the relation files). To make things simpler, the caller should expect
- * OldHeap to be closed on return, regardless CLUOPT_CONCURRENT. (The
- * AccessExclusiveLock is kept till the end of the transaction.)
+ * On return, OldHeap is closed but locked with AccessExclusiveLock - the lock
+ * will be released at end of the transaction.
  *
  * 'cmd' indicates which command is being executed, to be used for error
  * messages.
@@ -512,10 +519,12 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid,
 		/*
 		 * Make sure we're not in a transaction block.
 		 *
-		 * The reason is that repack_setup_logical_decoding() could deadlock
-		 * if there's an XID already assigned.  It would be possible to run in
-		 * a transaction block if we had no XID, but this restriction is
-		 * simpler for users to understand and we don't lose anything.
+		 * The reason is that repack_setup_logical_decoding() could wait
+		 * indefinitely for our XID to complete. (The deadlock detector would
+		 * not recognize it because we'd be waiting for ourselves, i.e. no
+		 * real lock conflict.) It would be possible to run in a transaction
+		 * block if we had no XID, but this restriction is simpler for users
+		 * to understand and we don't lose anything.
 		 */
 		PreventInTransactionBlock(isTopLevel, "REPACK (CONCURRENTLY)");
 
@@ -998,10 +1007,8 @@ rebuild_relation(Relation OldHeap, Relation index, bool verbose,
 		 * Note that the worker has to wait for all transactions with XID
 		 * already assigned to finish. If some of those transactions is
 		 * waiting for a lock conflicting with ShareUpdateExclusiveLock on our
-		 * table (e.g.  it runs CREATE INDEX), we can end up in a deadlock.
-		 * Not sure this risk is worth unlocking/locking the table (and its
-		 * clustering index) and checking again if it's still eligible for
-		 * REPACK CONCURRENTLY.
+		 * table (e.g. it runs CREATE INDEX), it should encounter ERROR in the
+		 * deadlock checking code.
 		 */
 		start_repack_decoding_worker(tableOid);
 
@@ -3123,10 +3130,18 @@ rebuild_relation_finish_concurrent(Relation NewHeap, Relation OldHeap,
 		LockRelationOid(OldHeap->rd_rel->reltoastrelid, AccessExclusiveLock);
 
 	/*
-	 * Tuples and pages of the old heap will be gone, but the heap will stay.
+	 * Now that we have all access-exclusive locks on all relations, we no
+	 * longer want other processes to error out when trying to acquire a
+	 * conflicting lock.  Therefore, unset our flag.
+	 */
+	MyProc->statusFlags &= ~PROC_IN_CONCURRENT_REPACK;
+
+	/*
+	 * Tuples and pages of the old heap will be gone, but the heap itself will
+	 * stay.  In order for predicate locks to continue to work, convert them
+	 * to relation-level locks.  We do this both for table and indexes.
 	 */
 	TransferPredicateLocksToHeapRelation(OldHeap);
-	/* The same for indexes. */
 	for (int i = 0; i < nind; i++)
 	{
 		Relation	index = ind_refs[i];
@@ -3346,9 +3361,11 @@ start_repack_decoding_worker(Oid relid)
 
 	/*
 	 * The decoding setup must be done before the caller can have XID assigned
-	 * for any reason, otherwise the worker might end up in a deadlock,
-	 * waiting for the caller's transaction to end. Therefore wait here until
-	 * the worker indicates that it has the logical decoding initialized.
+	 * for any reason, otherwise the worker might end up waiting for the
+	 * caller's transaction to end. (Deadlock detector does not consider this
+	 * a conflict because the worker is in the same locking group as the
+	 * backend that launched it.) Therefore wait here until the worker
+	 * indicates that it has the logical decoding initialized.
 	 */
 	ConditionVariablePrepareToSleep(&shared->cv);
 	for (;;)
diff --git a/src/backend/storage/lmgr/deadlock.c b/src/backend/storage/lmgr/deadlock.c
index b8962d875b6..3d3ec0da111 100644
--- a/src/backend/storage/lmgr/deadlock.c
+++ b/src/backend/storage/lmgr/deadlock.c
@@ -620,6 +620,21 @@ FindLockCycleRecurseMember(PGPROC *checkProc,
 						proc->statusFlags & PROC_IS_AUTOVACUUM)
 						blocking_autovacuum_proc = proc;
 
+					/*
+					 * Similarly, if we note that we're blocked by some process
+					 * running REPACK (CONCURRENTLY), just fail.  That process
+					 * is going to upgrade its lock at some point, and it would
+					 * be inappropriate for any other process to cause that
+					 * to fail.
+					 */
+					if (checkProc == MyProc &&
+						proc->statusFlags & PROC_IN_CONCURRENT_REPACK)
+						ereport(ERROR,
+								errcode(ERRCODE_OBJECT_IN_USE),
+								errmsg("could not wait for concurrent REPACK"),
+								errdetail("Process %d waits for REPACK running on process %d",
+									   MyProc->pid, proc->pid));
+
 					/* We're done looking at this proclock */
 					break;
 				}
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 1dad125706e..8ad9718f3d6 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -69,10 +69,12 @@ struct XidCache
 #define		PROC_AFFECTS_ALL_HORIZONS	0x20	/* this proc's xmin must be
 												 * included in vacuum horizons
 												 * in all databases */
+#define		PROC_IN_CONCURRENT_REPACK	0x40	/* REPACK (CONCURRENTLY) */
 
-/* flags reset at EOXact */
+/* flags reset at EOXact.  A bit of a misnomer ... */
 #define		PROC_VACUUM_STATE_MASK \
-	(PROC_IN_VACUUM | PROC_IN_SAFE_IC | PROC_VACUUM_FOR_WRAPAROUND)
+	(PROC_IN_VACUUM | PROC_IN_SAFE_IC | PROC_VACUUM_FOR_WRAPAROUND | \
+	 PROC_IN_CONCURRENT_REPACK)
 
 /*
  * Xmin-related flags. Make sure any flags that affect how the process' Xmin
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index 2cd7d87c533..f7663859fe2 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -15,6 +15,7 @@ REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 ISOLATION = basic \
 	    inplace \
 	    repack \
+	    repack_deadlock \
 	    repack_toast \
 	    syscache-update-pruned \
 	    heap_lock_update
diff --git a/src/test/modules/injection_points/expected/repack_deadlock.out b/src/test/modules/injection_points/expected/repack_deadlock.out
new file mode 100644
index 00000000000..a86e4767536
--- /dev/null
+++ b/src/test/modules/injection_points/expected/repack_deadlock.out
@@ -0,0 +1,63 @@
+Parsed test spec with 2 sessions
+
+starting permutation: wait_before_lock add_column wakeup_before_lock check1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step wait_before_lock: 
+	REPACK (CONCURRENTLY) repack_deadlock USING INDEX repack_deadlock_pkey;
+ <waiting ...>
+step add_column: 
+	alter table repack_deadlock add column noise text;
+ <waiting ...>
+step add_column: <... completed>
+ERROR:  could not wait for concurrent REPACK
+step wakeup_before_lock: 
+	SELECT injection_points_wakeup('repack-concurrently-before-lock');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step wait_before_lock: <... completed>
+step check1: 
+	INSERT INTO relfilenodes(node)
+	SELECT relfilenode FROM pg_class WHERE relname='repack_deadlock';
+
+	SELECT count(DISTINCT node) FROM relfilenodes;
+
+	SELECT i, j FROM repack_deadlock ORDER BY i, j;
+
+	INSERT INTO data_s1(i, j)
+	SELECT i, j FROM repack_deadlock;
+
+	SELECT count(*)
+	FROM data_s1 d1 FULL JOIN data_s2 d2 USING (i, j)
+	WHERE d1.i ISNULL OR d2.i ISNULL;
+
+count
+-----
+    1
+(1 row)
+
+i|j
+-+-
+1|1
+2|2
+3|3
+4|4
+(4 rows)
+
+count
+-----
+    4
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index a414abb924b..1cd88d6db65 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -46,6 +46,7 @@ tests += {
       'basic',
       'inplace',
       'repack',
+      'repack_deadlock',
       'repack_toast',
       'syscache-update-pruned',
       'heap_lock_update',
diff --git a/src/test/modules/injection_points/specs/repack_deadlock.spec b/src/test/modules/injection_points/specs/repack_deadlock.spec
new file mode 100644
index 00000000000..9d23a6588c2
--- /dev/null
+++ b/src/test/modules/injection_points/specs/repack_deadlock.spec
@@ -0,0 +1,83 @@
+# Test REPACK with a concurrent transaction that would cause a deadlock
+setup
+{
+	CREATE EXTENSION injection_points;
+
+	CREATE TABLE repack_deadlock(i int PRIMARY KEY, j int);
+	INSERT INTO repack_deadlock(i, j) VALUES (1, 1), (2, 2), (3, 3), (4, 4);
+
+	CREATE TABLE relfilenodes(node oid);
+
+	CREATE TABLE data_s1(i int, j int);
+	CREATE TABLE data_s2(i int, j int);
+}
+
+teardown
+{
+	DROP TABLE repack_deadlock;
+	DROP EXTENSION injection_points;
+
+	DROP TABLE relfilenodes;
+	DROP TABLE data_s1;
+	DROP TABLE data_s2;
+}
+
+session s1
+setup
+{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('repack-concurrently-before-lock', 'wait');
+}
+# Perform the initial load and wait for s2 to do some data changes.
+step wait_before_lock
+{
+	REPACK (CONCURRENTLY) repack_deadlock USING INDEX repack_deadlock_pkey;
+}
+# Check the table from the perspective of s1.
+#
+# Besides the contents, we also check that relfilenode has changed.
+
+# Have each session write the contents into a table and use FULL JOIN to check
+# if the outputs are identical.
+step check1
+{
+	INSERT INTO relfilenodes(node)
+	SELECT relfilenode FROM pg_class WHERE relname='repack_deadlock';
+
+	SELECT count(DISTINCT node) FROM relfilenodes;
+
+	SELECT i, j FROM repack_deadlock ORDER BY i, j;
+
+	INSERT INTO data_s1(i, j)
+	SELECT i, j FROM repack_deadlock;
+
+	SELECT count(*)
+	FROM data_s1 d1 FULL JOIN data_s2 d2 USING (i, j)
+	WHERE d1.i ISNULL OR d2.i ISNULL;
+}
+teardown
+{
+	SELECT injection_points_detach('repack-concurrently-before-lock');
+}
+
+session s2
+# Change the existing data. UPDATE changes both key and non-key columns. Also
+# update one row twice to test whether tuple version generated by this session
+# can be found.
+step add_column
+{
+	alter table repack_deadlock add column noise text;
+}
+
+step wakeup_before_lock
+{
+	SELECT injection_points_wakeup('repack-concurrently-before-lock');
+}
+
+# Test if data changes introduced while one session is performing REPACK
+# CONCURRENTLY find their way into the table.
+permutation
+	wait_before_lock
+	add_column
+	wakeup_before_lock
+	check1
-- 
2.47.3


--mdsv5bdgfjjj6d77
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
	filename="v46-0007-Teach-snapshot-builder-to-skip-transactions-runn.patch"



^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--





^ permalink  raw  reply  [nested|flat] 281+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





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* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





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* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28 Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 281+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






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