From e476eedd0c06e81ee6d76fd8dc23eb5d54f1ba0b Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 21 Feb 2011 21:18:25 -0500 Subject: Fix dangling-pointer problem in before-row update trigger processing. ExecUpdate checked for whether ExecBRUpdateTriggers had returned a new tuple value by seeing if the returned tuple was pointer-equal to the old one. But the "old one" was in estate->es_junkFilter's result slot, which would be scribbled on if we had done an EvalPlanQual update in response to a concurrent update of the target tuple; therefore we were comparing a dangling pointer to a live one. Given the right set of circumstances we could get a false match, resulting in not forcing the tuple to be stored in the slot we thought it was stored in. In the case reported by Maxim Boguk in bug #5798, this led to "cannot extract system attribute from virtual tuple" failures when trying to do "RETURNING ctid". I believe there is a very-low-probability chance of more serious errors, such as generating incorrect index entries based on the original rather than the trigger-modified version of the row. In HEAD, change all of ExecBRInsertTriggers, ExecIRInsertTriggers, ExecBRUpdateTriggers, and ExecIRUpdateTriggers so that they continue to have similar APIs. In the back branches I just changed ExecBRUpdateTriggers, since there is no bug in the ExecBRInsertTriggers case. --- src/include/commands/trigger.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'src/include/commands/trigger.h') diff --git a/src/include/commands/trigger.h b/src/include/commands/trigger.h index 27bb6e93c75..32214e60060 100644 --- a/src/include/commands/trigger.h +++ b/src/include/commands/trigger.h @@ -132,10 +132,10 @@ extern void ExecBSUpdateTriggers(EState *estate, ResultRelInfo *relinfo); extern void ExecASUpdateTriggers(EState *estate, ResultRelInfo *relinfo); -extern HeapTuple ExecBRUpdateTriggers(EState *estate, +extern TupleTableSlot *ExecBRUpdateTriggers(EState *estate, ResultRelInfo *relinfo, ItemPointer tupleid, - HeapTuple newtuple); + TupleTableSlot *slot); extern void ExecARUpdateTriggers(EState *estate, ResultRelInfo *relinfo, ItemPointer tupleid, -- cgit v1.2.3