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authorAndres Freund2015-01-29 16:49:03 +0000
committerAndres Freund2015-01-29 21:48:45 +0000
commit17792bfc5b62f42a9dfbd2ac408e7e71c239330a (patch)
treee22cbed2e16b1f590232fb23a15ff39e90a6e57b
parented127002d8c592610bc8e716759a1a70657483b6 (diff)
Properly terminate the array returned by GetLockConflicts().
GetLockConflicts() has for a long time not properly terminated the returned array. During normal processing the returned array is zero initialized which, while not pretty, is sufficient to be recognized as a invalid virtual transaction id. But the HotStandby case is more than aesthetically broken: The allocated (and reused) array is neither zeroed upon allocation, nor reinitialized, nor terminated. Not having a terminating element means that the end of the array will not be recognized and that recovery conflict handling will thus read ahead into adjacent memory. Only terminating when hitting memory content that looks like a invalid virtual transaction id. Luckily this seems so far not have caused significant problems, besides making recovery conflict more expensive. Discussion: 20150127142713.GD29457@awork2.anarazel.de Backpatch into all supported branches.
-rw-r--r--src/backend/storage/lmgr/lock.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
index 61c8d216f75..1eb2d4b68da 100644
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -2804,6 +2804,8 @@ GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode)
* on this lockable object.
*/
LWLockRelease(partitionLock);
+ vxids[count].backendId = InvalidBackendId;
+ vxids[count].localTransactionId = InvalidLocalTransactionId;
return vxids;
}
@@ -2857,6 +2859,8 @@ GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode)
if (count > MaxBackends) /* should never happen */
elog(PANIC, "too many conflicting locks found");
+ vxids[count].backendId = InvalidBackendId;
+ vxids[count].localTransactionId = InvalidLocalTransactionId;
return vxids;
}