From 1452a0bb87c78812372f103de14cb6492a932ac6 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 18 Mar 2021 20:50:56 -0400 Subject: [PATCH] Don't run RelationInitTableAccessMethod in a long-lived context. Some code paths in this function perform syscache lookups, which can lead to table accesses and possibly leakage of cruft into the caller's context. If said context is CacheMemoryContext, we eventually will have visible bloat. But fixing this is no harder than moving one memory context switch step. (The other callers don't have a problem.) Andres Freund and I independently found this via valgrind testing. Back-patch to v12 where this code was added. Discussion: https://postgr.es/m/20210317023101.anvejcfotwka6gaa@alap3.anarazel.de Discussion: https://postgr.es/m/3816764.1616104288@sss.pgh.pa.us --- src/backend/utils/cache/relcache.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index c6e3dc3016..2babf52538 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -3359,6 +3359,13 @@ RelationBuildLocalRelation(const char *relname, rel->rd_rel->relam = accessmtd; + /* + * RelationInitTableAccessMethod will do syscache lookups, so we mustn't + * run it in CacheMemoryContext. Fortunately, the remaining steps don't + * require a long-lived current context. + */ + MemoryContextSwitchTo(oldcxt); + if (relkind == RELKIND_RELATION || relkind == RELKIND_SEQUENCE || relkind == RELKIND_TOASTVALUE || @@ -3382,11 +3389,6 @@ RelationBuildLocalRelation(const char *relname, */ EOXactListAdd(rel); - /* - * done building relcache entry. - */ - MemoryContextSwitchTo(oldcxt); - /* It's fully valid */ rel->rd_isvalid = true;