From e46753e9b935516b296bff8d46b9234bc46ee596 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 11 Jun 2013 17:26:53 -0400 Subject: [PATCH] Fix cache flush hazard in cache_record_field_properties(). We need to increment the refcount on the composite type's cached tuple descriptor while we do lookups of its column types. Otherwise a cache flush could occur and release the tuple descriptor before we're done with it. This fails reliably with -DCLOBBER_CACHE_ALWAYS, but the odds of a failure in a production build seem rather low (since the pfree'd descriptor typically wouldn't get scribbled on immediately). That may explain the lack of any previous reports. Buildfarm issue noted by Christian Ullrich. Back-patch to 9.1 where the bogus code was added. --- src/backend/utils/cache/typcache.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/src/backend/utils/cache/typcache.c b/src/backend/utils/cache/typcache.c index afbe121f7af..5fd02958cf1 100644 --- a/src/backend/utils/cache/typcache.c +++ b/src/backend/utils/cache/typcache.c @@ -578,6 +578,9 @@ cache_record_field_properties(TypeCacheEntry *typentry) load_typcache_tupdesc(typentry); tupdesc = typentry->tupDesc; + /* Must bump the refcount while we do additional catalog lookups */ + IncrTupleDescRefCount(tupdesc); + /* Have each property if all non-dropped fields have the property */ newflags = (TCFLAGS_HAVE_FIELD_EQUALITY | TCFLAGS_HAVE_FIELD_COMPARE); @@ -601,6 +604,8 @@ cache_record_field_properties(TypeCacheEntry *typentry) break; } typentry->flags |= newflags; + + DecrTupleDescRefCount(tupdesc); } typentry->flags |= TCFLAGS_CHECKED_FIELD_PROPERTIES; }