From 55566c9a740144439b54ff3aacbd43d11b6de52f Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Fri, 7 Mar 2014 13:25:11 +0200 Subject: Fix dangling smgr_owner pointer when a fake relcache entry is freed. A fake relcache entry can "own" a SmgrRelation object, like a regular relcache entry. But when it was free'd, the owner field in SmgrRelation was not cleared, so it was left pointing to free'd memory. Amazingly this apparently hasn't caused crashes in practice, or we would've heard about it earlier. Andres found this with Valgrind. Report and fix by Andres Freund, with minor modifications by me. Backpatch to all supported versions. --- src/backend/access/transam/xlogutils.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'src/backend/access/transam/xlogutils.c') diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c index f1918f6b078..05e74de9211 100644 --- a/src/backend/access/transam/xlogutils.c +++ b/src/backend/access/transam/xlogutils.c @@ -445,6 +445,9 @@ CreateFakeRelcacheEntry(RelFileNode rnode) void FreeFakeRelcacheEntry(Relation fakerel) { + /* make sure the fakerel is not referenced by the SmgrRelation anymore */ + if (fakerel->rd_smgr != NULL) + smgrclearowner(&fakerel->rd_smgr, fakerel->rd_smgr); pfree(fakerel); } -- cgit v1.2.3