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Fix two memory leaks around force-storing tuples in slots.

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As reported by Tom, when ExecStoreMinimalTuple() had to perform a
conversion to store the minimal tuple in the slot, it forgot to
respect the shouldFree flag, and leaked the tuple into the current
memory context if true.  Fix that by freeing the tuple in that case.

Looking at the relevant code made me (Andres) realize that not having
the shouldFree parameter to ExecForceStoreHeapTuple() was a bad
idea. Some callers had to locally implement the necessary logic, and
in one case it was missing, creating a potential per-group leak in
non-hashed aggregation.

The choice to not free the tuple in ExecComputeStoredGenerated() is
not pretty, but not introduced by this commit - I'll start a separate
discussion about it.

Reported-By: Tom Lane
Discussion: https://postgr.es/m/366.1555382816@sss.pgh.pa.us
This commit is contained in:
Andres Freund
2019-04-19 11:33:37 -07:00
parent 4d5840cea9
commit 88e6ad3054
7 changed files with 41 additions and 20 deletions
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4
contrib/postgres_fdw/postgres_fdw.c
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@ -3711,9 +3711,7 @@ store_returning_result(PgFdwModifyState *fmstate,
* The returning slot will not necessarily be suitable to store
* heaptuples directly, so allow for conversion.
*/
ExecForceStoreHeapTuple(newtup, slot);
ExecMaterializeSlot(slot);
pfree(newtup);
ExecForceStoreHeapTuple(newtup, slot, true);
}
PG_CATCH();
{