From 42e609852671acabc96ef17ec06a495aa992cb23 Mon Sep 17 00:00:00 2001 From: Sami Imseih Date: Thu, 2 Jul 2026 16:15:05 -0500 Subject: [PATCH v2 1/3] Add validations for required callbacks during pgstat_register_kind() pgstat_register_kind() did not validate that required callbacks were set, which could lead to NULL pointer dereferences. For fixed-amount kinds, init_shmem_cb, reset_all_cb, and snapshot_cb are called unconditionally. A missing callback crashes the server at startup or during recovery. For variable-numbered kinds, flush_pending_cb is called unconditionally when flushing pending entries. If pending_size is set but flush_pending_cb is NULL, the server crashes when that callback is run. Add validation checks at registration time for custom kinds. --- src/backend/utils/activity/pgstat.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c index c4fa14f138f..f6223d2a3dd 100644 --- a/src/backend/utils/activity/pgstat.c +++ b/src/backend/utils/activity/pgstat.c @@ -1533,11 +1533,34 @@ pgstat_register_kind(PgStat_Kind kind, const PgStat_KindInfo *kind_info) ereport(ERROR, (errmsg("custom cumulative statistics property is invalid"), errhint("Custom cumulative statistics require a shared memory size for fixed-numbered objects."))); + if (kind_info->init_shmem_cb == NULL) + ereport(ERROR, + (errmsg("failed to register custom cumulative statistics \"%s\" with ID %u", kind_info->name, kind), + errhint("Custom cumulative statistics require a \"%s\" callback for fixed-numbered objects.", + "init_shmem_cb"))); + if (kind_info->reset_all_cb == NULL) + ereport(ERROR, + (errmsg("failed to register custom cumulative statistics \"%s\" with ID %u", kind_info->name, kind), + errhint("Custom cumulative statistics require a \"%s\" callback for fixed-numbered objects.", + "reset_all_cb"))); + if (kind_info->snapshot_cb == NULL) + ereport(ERROR, + (errmsg("failed to register custom cumulative statistics \"%s\" with ID %u", kind_info->name, kind), + errhint("Custom cumulative statistics require a \"%s\" callback for fixed-numbered objects.", + "snapshot_cb"))); if (kind_info->track_entry_count) ereport(ERROR, (errmsg("custom cumulative statistics property is invalid"), errhint("Custom cumulative statistics cannot use entry count tracking for fixed-numbered objects."))); } + else + { + if (kind_info->pending_size > 0 && kind_info->flush_pending_cb == NULL) + ereport(ERROR, + (errmsg("failed to register custom cumulative statistics \"%s\" with ID %u", kind_info->name, kind), + errhint("Custom cumulative statistics require a \"%s\" callback when pending_size is set.", + "flush_pending_cb"))); + } /* * If pgstat_kind_custom_infos is not available yet, allocate it. -- 2.50.1 (Apple Git-155)