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Guard against table-AM-less relations in planner.

2022年10月17日 15:35:23 +0000 (11:35 -0400)

The executor will dump core if it's asked to execute a seqscan on
a relation having no table AM, such as a view. While that shouldn't
really happen, it's possible to get there via catalog corruption,
such as a missing ON SELECT rule. It seems worth installing a defense
against that. There are multiple plausible places for such a defense,
but I picked the planner's get_relation_info().

Per discussion of bug #17646 from Kui Liu. Back-patch to v12 where
the tableam APIs were introduced; in older versions you won't get a
SIGSEGV, so it seems less pressing.

Discussion: https://postgr.es/m/17646-70c93cfa40365776@postgresql.org

src/backend/optimizer/util/plancat.c patch | blob | blame | history

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c

index 6d5718ee4cb09cccbd5bd8963d0e6bb21d555db8..9defe378362d3f1cba0e682145313d0438ea3b89 100644 (file)

--- a/src/backend/optimizer/util/plancat.c

+++ b/src/backend/optimizer/util/plancat.c

@@ -127,6 +127,24 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,

relation = table_open(relationObjectId, NoLock);

+ /*

+ * Relations without a table AM can be used in a query only if they are of

+ * special-cased relkinds. This check prevents us from crashing later if,

+ * for example, a view's ON SELECT rule has gone missing. Note that

+ * table_open() already rejected indexes and composite types; spell the