Fix incorrect memory access in VACUUM FULL with invalid toast indexes

michaelpq · michaelpq · commit 911eda9f3cc3 · 2024-09-27T09:40:21.000+09:00
An invalid toast index is skipped in reindex_relation(). These would be remnants of a failed REINDEX CONCURRENTLY and they should never been rebuilt as there can only be one valid toast index at a time. REINDEX_REL_SUPPRESS_INDEX_USE, used by CLUSTER and VACUUM FULL, needs to maintain a list of the indexes being processed. The list of indexes is retrieved from the relation cache, and includes invalid indexes. The code has missed that invalid toast indexes are ignored in reindex_relation() as this leads to a hard failure in reindex_index(), and they were left in the reindex pending list, making the list inconsistent when rechecked. The incorrect memory access was happening when scanning pg_class for the refresh of pg_database.datfrozenxid, when doing a scan of pg_class. This issue exists since REINDEX CONCURRENTLY exists, where invalid toast indexes can exist, so backpatch all the way down. Reported-by: Alexander Lakhin Author: Tender Wang Discussion: https://postgr.es/m/18630-9aed99c38830657d@postgresql.org Backpatch-through: 12
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
@@ -3859,6 +3859,14 @@ reindex_relation(Oid relid, int flags, int options)
 					 errmsg("cannot reindex invalid index \"%s.%s\" on TOAST table, skipping",
 							get_namespace_name(indexNamespaceId),
 							get_rel_name(indexOid))));
+
+			/*
+			 * Remove this invalid toast index from the reindex pending list,
+			 * as it is skipped here due to the hard failure that would happen
+			 * in reindex_index(), should we try to process it.
+			 */
+			if (flags & REINDEX_REL_SUPPRESS_INDEX_USE)
+				RemoveReindexPending(indexOid);
 			continue;
 		}
 
