From b4f14d2e433bf9f2499f07bcaca07b9ff13d641b Mon Sep 17 00:00:00 2001 From: Masahiko Sawada Date: Wed, 26 Jul 2023 14:41:23 +0900 Subject: [PATCH] Fix crash with RemoveFromWaitQueue() when detecting a deadlock. Commit 5764f611e used dclist_delete_from() to remove the proc from the wait queue. However, since it doesn't clear dist_node's next/prev to NULL, it could call RemoveFromWaitQueue() twice: when the process detects a deadlock and then when cleaning up locks on aborting the transaction. The waiting lock information is cleared in the first call, so it led to a crash in the second call. Backpatch to v16, where the change was introduced. Bug: #18031 Reported-by: Justin Pryzby, Alexander Lakhin Reviewed-by: Andres Freund Discussion: https://postgr.es/m/ZKy4AdrLEfbqrxGJ%40telsasoft.com Discussion: https://postgr.es/m/18031-ebe2d08cb405f6cc@postgresql.org Backpatch-through: 16 --- src/backend/storage/lmgr/lock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c index f595bce31b..ec6240fbae 100644 --- a/src/backend/storage/lmgr/lock.c +++ b/src/backend/storage/lmgr/lock.c @@ -1881,7 +1881,7 @@ RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode) Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods)); /* Remove proc from lock's wait queue */ - dclist_delete_from(&waitLock->waitProcs, &proc->links); + dclist_delete_from_thoroughly(&waitLock->waitProcs, &proc->links); /* Undo increments of request counts by waiting process */ Assert(waitLock->nRequested > 0);