Ensure that slots are zeroed before use

danielgustafsson · danielgustafsson · commit e63ce9e8d6ac · 2021-10-26T10:40:08.000+02:00
The previous coding relied on the memory for the slots being zeroed elsewhere, which while it was true in this case is not an contract which is guaranteed to hold. Explicitly clear the tts_isnull array to ensure that the slots are filled from a known state. Backpatch to v14 where the catalog multi-inserts were introduced. Reviewed-by: Michael Paquier <michael@paquier.xyz> Discussion: https://postgr.es/m/CAJ7c6TP0AowkUgNL6zcAK-s5HYsVHVBRWfu69FRubPpfwZGM9A@mail.gmail.com Backpatch-through: 14
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
@@ -764,6 +764,9 @@ InsertPgAttributeTuples(Relation pg_attribute_rel,
 
 		ExecClearTuple(slot[slotCount]);
 
+		memset(slot[slotCount]->tts_isnull, false,
+			   slot[slotCount]->tts_tupleDescriptor->natts * sizeof(bool));
+
 		if (new_rel_oid != InvalidOid)
 			slot[slotCount]->tts_values[Anum_pg_attribute_attrelid - 1] = ObjectIdGetDatum(new_rel_oid);
 		else
diff --git a/src/backend/catalog/pg_shdepend.c b/src/backend/catalog/pg_shdepend.c
@@ -903,6 +903,9 @@ copyTemplateDependencies(Oid templateDbId, Oid newDbId)
 
 		ExecClearTuple(slot[slot_stored_count]);
 
+		memset(slot[slot_stored_count]->tts_isnull, false,
+			   slot[slot_stored_count]->tts_tupleDescriptor->natts * sizeof(bool));
+
 		shdep = (Form_pg_shdepend) GETSTRUCT(tup);
 
 		slot[slot_stored_count]->tts_values[Anum_pg_shdepend_dbid - 1] = ObjectIdGetDatum(newDbId);
