From d411d6eff1b7e91de0fecece08acc6b6eca04d6d 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') diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c index 1811c91d581..8f0bbc21dbb 100644 --- a/src/backend/access/transam/xlogutils.c +++ b/src/backend/access/transam/xlogutils.c @@ -413,6 +413,9 @@ 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