From: Thomas Munro Date: Sat, 29 May 2021 02:48:15 +0000 (+1200) Subject: Fix race condition when sharing tuple descriptors. X-Git-Tag: REL_14_BETA2~128 X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=b1d6538903504904db44679355ac109aeda01737;p=postgresql.git Fix race condition when sharing tuple descriptors. Parallel query processes that called BlessTupleDesc() for identical tuple descriptors at the same moment could crash. There was code to handle that rare case, but it dereferenced a bogus DSA pointer. Repair. Back-patch to 11, where commit cc5f8136 added support for sharing tuple descriptors in parallel queries. Reported-by: Eric Thinnes Discussion: https://postgr.es/m/99aaa2eb-e194-bf07-c29a-1a76b4f2bcf9%40gmx.de --- diff --git a/src/backend/utils/cache/typcache.c b/src/backend/utils/cache/typcache.c index 35c8cf7b244..de96e96c8fd 100644 --- a/src/backend/utils/cache/typcache.c +++ b/src/backend/utils/cache/typcache.c @@ -2822,7 +2822,7 @@ find_or_make_matching_shared_tupledesc(TupleDesc tupdesc) Assert(record_table_entry->key.shared); result = (TupleDesc) dsa_get_address(CurrentSession->area, - record_table_entry->key.shared); + record_table_entry->key.u.shared_tupdesc); Assert(result->tdrefcount == -1); return result;