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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 originallywritten (commit1785ace), but missed thatthe pfree needed to be protected with an if-test. Just to make sure thingsare left in a clean state, reset numLockOwners as well.Per low-memory testing by Andreas Seltenreich. Back-patch to all supportedbranches.

1 parentf38070d commite32c5f1Copy full SHA for e32c5f1

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src/backend/storage/lmgr
- lock.c

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`‎src/backend/storage/lmgr/lock.c`

Lines changed: 4 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -758,7 +758,7 @@ LockAcquireExtended(const LOCKTAG *locktag,`
`758`	`758`	`locallock->numLockOwners=0;`
`759`	`759`	`locallock->maxLockOwners=8;`
`760`	`760`	`locallock->holdsStrongLockCount= FALSE;`
`761`		`-locallock->lockOwners=NULL;`
	`761`	`+locallock->lockOwners=NULL;/* in case next line fails */`
`762`	`762`	`locallock->lockOwners= (LOCALLOCKOWNER*)`
`763`	`763`	`MemoryContextAlloc(TopMemoryContext,`
`764`	`764`	`locallock->maxLockOwners*sizeof(LOCALLOCKOWNER));`
`@@ -1227,7 +1227,9 @@ RemoveLocalLock(LOCALLOCK *locallock)`
`1227`	`1227`	`if (locallock->lockOwners[i].owner!=NULL)`
`1228`	`1228`	`ResourceOwnerForgetLock(locallock->lockOwners[i].owner,locallock);`
`1229`	`1229`	`}`
`1230`		`-pfree(locallock->lockOwners);`
	`1230`	`+locallock->numLockOwners=0;`
	`1231`	`+if (locallock->lockOwners!=NULL)`
	`1232`	`+pfree(locallock->lockOwners);`
`1231`	`1233`	`locallock->lockOwners=NULL;`
`1232`	`1234`
`1233`	`1235`	`if (locallock->holdsStrongLockCount)`

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Commite32c5f1

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`‎src/backend/storage/lmgr/lock.c`

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