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Check syscache result in AlterStatistics

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The syscache lookup may return NULL even for valid OID, for example due
to a concurrent DROP STATISTICS, so a HeapTupleIsValid is necessary.
Without it, it may fail with a segfault.

Reported by Alexander Lakhin, patch by me. Backpatch to 13, where ALTER
STATISTICS ... SET STATISTICS was introduced.

Backpatch-through: 13
Discussion: https://postgr.es/m/17372-bf3b6e947e35ae77%40postgresql.org
This commit is contained in:
Tomas Vondra 2022-01-23 02:49:41 +01:00
parent 62e28097ce
commit 6d554e3fcd
1 changed files with 2 additions and 0 deletions
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2
src/backend/commands/statscmds.c
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@ -657,6 +657,8 @@ AlterStatistics(AlterStatsStmt *stmt)
rel = table_open(StatisticExtRelationId, RowExclusiveLock);
oldtup = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(stxoid));
if (!HeapTupleIsValid(oldtup))
elog(ERROR, "cache lookup failed for extended statistics object %u", stxoid);
/* Must be owner of the existing statistics object */
if (!pg_statistics_object_ownercheck(stxoid, GetUserId()))