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Fix dangling-pointer problem in before-row update trigger processing.

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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.
This commit is contained in:
Tom Lane
2011-02-21 21:18:04 -05:00
parent fee7802770
commit a210be7720
4 changed files with 161 additions and 144 deletions
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18
src/include/commands/trigger.h
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@ -132,16 +132,16 @@ extern void ExecBSInsertTriggers(EState *estate,
ResultRelInfo *relinfo);
extern void ExecASInsertTriggers(EState *estate,
ResultRelInfo *relinfo);
extern HeapTuple ExecBRInsertTriggers(EState *estate,
extern TupleTableSlot *ExecBRInsertTriggers(EState *estate,
ResultRelInfo *relinfo,
HeapTuple trigtuple);
TupleTableSlot *slot);
extern void ExecARInsertTriggers(EState *estate,
ResultRelInfo *relinfo,
HeapTuple trigtuple,
List *recheckIndexes);
extern HeapTuple ExecIRInsertTriggers(EState *estate,
extern TupleTableSlot *ExecIRInsertTriggers(EState *estate,
ResultRelInfo *relinfo,
HeapTuple trigtuple);
TupleTableSlot *slot);
extern void ExecBSDeleteTriggers(EState *estate,
ResultRelInfo *relinfo);
extern void ExecASDeleteTriggers(EState *estate,
@ -160,20 +160,20 @@ extern void ExecBSUpdateTriggers(EState *estate,
ResultRelInfo *relinfo);
extern void ExecASUpdateTriggers(EState *estate,
ResultRelInfo *relinfo);
extern HeapTuple ExecBRUpdateTriggers(EState *estate,
extern TupleTableSlot *ExecBRUpdateTriggers(EState *estate,
EPQState *epqstate,
ResultRelInfo *relinfo,
ItemPointer tupleid,
HeapTuple newtuple);
TupleTableSlot *slot);
extern void ExecARUpdateTriggers(EState *estate,
ResultRelInfo *relinfo,
ItemPointer tupleid,
HeapTuple newtuple,
List *recheckIndexes);
extern HeapTuple ExecIRUpdateTriggers(EState *estate,
extern TupleTableSlot *ExecIRUpdateTriggers(EState *estate,
ResultRelInfo *relinfo,
HeapTuple oldtuple,
HeapTuple newtuple);
HeapTuple trigtuple,
TupleTableSlot *slot);
extern void ExecBSTruncateTriggers(EState *estate,
ResultRelInfo *relinfo);
extern void ExecASTruncateTriggers(EState *estate,