Fix memory allocation/copy mistakes.

Etsuro Fujita · Etsuro Fujita · commit 5201bba266d7 · 2025-05-03T20:00:00.000+09:00
The previous code was allocating more memory and copying more data than necessary because it specified the wrong PgStat_KindInfo member as the size argument for MemoryContextAlloc and memcpy, respectively. Although these issues exist since 5891c7a, there have been no reports from the field. So for now, it seems sufficient to fix them in master. Author: Etsuro Fujita <etsuro.fujita@gmail.com> Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> Reviewed-by: Gurjeet Singh <gurjeet@singh.im> Discussion: https://postgr.es/m/CAPmGK15eTRCZTnfgQ4EuBNo%3DQLYGFEbXS_7m2dXqtkcT7L8qrQ%40mail.gmail.com
diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
@@ -1187,7 +1187,7 @@ pgstat_build_snapshot(void)
 		Assert(!found);
 
 		entry->data = MemoryContextAlloc(pgStatLocal.snapshot.context,
-										 kind_info->shared_size);
+										 pgstat_get_entry_len(kind));
 
 		/*
 		 * Acquire the LWLock directly instead of using
@@ -1196,7 +1196,7 @@ pgstat_build_snapshot(void)
 		LWLockAcquire(&stats_data->lock, LW_SHARED);
 		memcpy(entry->data,
 			   pgstat_get_entry_data(kind, stats_data),
-			   kind_info->shared_size);
+			   pgstat_get_entry_len(kind));
 		LWLockRelease(&stats_data->lock);
 	}
 	dshash_seq_term(&hstat);
