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commit    8afec4ef67a2fcec2ad0537fad5bc66e4388bc41
Author:   Daniel Gustafsson <dgustafsson@postgresql.org>
Date:     Thu Mar 27 21:57:34 2025 +0000

    Fix guc_malloc calls for consistency and OOM checks
    
    check_createrole_self_grant and check_synchronized_standby_slots
    were allocating memory on a LOG elevel without checking if the
    allocation succeeded or not, which would have led to a segfault
    on allocation failure.
    
    On top of that, a number of callsites were using the ERROR level,
    relying on erroring out rather than returning false to allow the
    GUC machinery handle it gracefully.  Other callsites used WARNING
    instead of LOG.  While neither being not wrong, this changes all
    check_ functions do it consistently with LOG.
    
    init_custom_variable gets a promoted elevel to FATAL to keep
    the guc_malloc error handling in line with the rest of the
    error handling in that function which already call FATAL.  If
    we encounter an OOM in this callsite there is no graceful
    handling to be had, better to error out hard.
    
    Backpatch the fix to check_createrole_self_grant down to v16
    and the fix to check_synchronized_standby_slots down to v17
    where they were introduced.
    
    Author: Daniel Gustafsson <daniel@yesql.se>
    Reported-by: Nikita <pm91.arapov@gmail.com>
    Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
    Bug: #18845
    Discussion: https://postgr.es/m/18845-582c6e10247377ec@postgresql.org
    Backpatch-through: 16


 src/backend/commands/user.c    | 2 ++
 src/backend/replication/slot.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index e204eb5e5d1..aed01cf4cae 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -2553,6 +2553,8 @@ check_createrole_self_grant(char **newval, void **extra, GucSource source)
 	list_free(elemlist);
 
 	result = (unsigned *) guc_malloc(LOG, sizeof(unsigned));
+	if (!result)
+		return false;
 	*result = options;
 	*extra = result;
 
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 780d22afbca..a1d4768623f 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -2521,6 +2521,8 @@ check_synchronized_standby_slots(char **newval, void **extra, GucSource source)
 
 	/* GUC extra value must be guc_malloc'd, not palloc'd */
 	config = (SyncStandbySlotsConfigData *) guc_malloc(LOG, size);
+	if (!config)
+		return false;
 
 	/* Transform the data into SyncStandbySlotsConfigData */
 	config->nslotnames = list_length(elemlist);


[parent: 51d038da8280]