From 553ce7e9a8d147cae75f0656a628c29dcbe498d8 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sun, 20 Sep 2015 16:48:44 -0400 Subject: [PATCH] Be more wary about partially-valid LOCALLOCK data in RemoveLocalLock(). RemoveLocalLock() must consider the possibility that LockAcquireExtended() failed to palloc the initial space for a locallock's lockOwners array. I had evidently meant to cope with this hazard when the code was originally written (commit 1785acebf2ed14fd66955e2d9a55d77a025f418d), but missed that the pfree needed to be protected with an if-test. Just to make sure things are left in a clean state, reset numLockOwners as well. Per low-memory testing by Andreas Seltenreich. Back-patch to all supported branches. --- src/backend/storage/lmgr/lock.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c index 5269b2d10e..d5786ca53a 100644 --- a/src/backend/storage/lmgr/lock.c +++ b/src/backend/storage/lmgr/lock.c @@ -646,7 +646,7 @@ LockAcquireExtended(const LOCKTAG *locktag, locallock->nLocks = 0; locallock->numLockOwners = 0; locallock->maxLockOwners = 8; - locallock->lockOwners = NULL; + locallock->lockOwners = NULL; /* in case next line fails */ locallock->lockOwners = (LOCALLOCKOWNER *) MemoryContextAlloc(TopMemoryContext, locallock->maxLockOwners * sizeof(LOCALLOCKOWNER)); @@ -1004,8 +1004,11 @@ RemoveLocalLock(LOCALLOCK *locallock) if (locallock->lockOwners[i].owner != NULL) ResourceOwnerForgetLock(locallock->lockOwners[i].owner, locallock); } - pfree(locallock->lockOwners); + locallock->numLockOwners = 0; + if (locallock->lockOwners != NULL) + pfree(locallock->lockOwners); locallock->lockOwners = NULL; + if (!hash_search(LockMethodLocalHash, (void *) &(locallock->tag), HASH_REMOVE, NULL)) -- 2.40.0