From ab8c84db2f7af008151b848cf1d6a4672a39eecd Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 13 Aug 2014 11:27:28 -0400 Subject: [PATCH] Prevent memory leaks in RelationGetIndexList, RelationGetIndexAttrBitmap. When replacing rd_indexlist, rd_indexattr, etc, we neglected to pfree any old value of these fields. Under ordinary circumstances, the old value would always be NULL, so this seemed reasonable enough. However, in cases where we're rebuilding a system catalog's relcache entry and another cache flush occurs on that same catalog meanwhile, it's possible for the field to not be NULL when we return to the outer level, because we already refilled it while recovering from the inner flush. This leads to a fairly small session-lifespan leak in CacheMemoryContext. In real-world usage the leak would be too small to notice; but in testing with CLOBBER_CACHE_RECURSIVELY the leakage can add up to the point of causing OOM failures, as reported by Tomas Vondra. The issue has been there a long time, but it only seems worth fixing in HEAD, like the previous fix in this area (commit 078b2ed291c758e7). --- src/backend/utils/cache/relcache.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 10d300a3e8..e4697f68ae 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -3646,6 +3646,7 @@ RelationGetIndexList(Relation relation) ScanKeyData skey; HeapTuple htup; List *result; + List *oldlist; char replident = relation->rd_rel->relreplident; Oid oidIndex = InvalidOid; Oid pkeyIndex = InvalidOid; @@ -3737,6 +3738,7 @@ RelationGetIndexList(Relation relation) /* Now save a copy of the completed list in the relcache entry. */ oldcxt = MemoryContextSwitchTo(CacheMemoryContext); + oldlist = relation->rd_indexlist; relation->rd_indexlist = list_copy(result); relation->rd_oidindex = oidIndex; if (replident == REPLICA_IDENTITY_DEFAULT && OidIsValid(pkeyIndex)) @@ -3748,6 +3750,9 @@ RelationGetIndexList(Relation relation) relation->rd_indexvalid = 1; MemoryContextSwitchTo(oldcxt); + /* Don't leak the old list, if there is one */ + list_free(oldlist); + return result; } @@ -4141,6 +4146,14 @@ RelationGetIndexAttrBitmap(Relation relation, IndexAttrBitmapKind attrKind) list_free(indexoidlist); + /* Don't leak the old values of these bitmaps, if any */ + bms_free(relation->rd_indexattr); + relation->rd_indexattr = NULL; + bms_free(relation->rd_keyattr); + relation->rd_keyattr = NULL; + bms_free(relation->rd_idattr); + relation->rd_idattr = NULL; + /* * Now save copies of the bitmaps in the relcache entry. We intentionally * set rd_indexattr last, because that's the one that signals validity of