Re: BUG #16036: Segmentation fault while doing an update

Hi,

On 2019-10-03 23:26:01 -0400, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > So I think what we need to do is:
> > 1) only call ExecCopySlot() if slot != newslot - this fixes the crash
> > 2) Add an assert to ExecCopySlot() ensuring source and target slot are
> >    distinct
> > 3) Figure out why our tests didn't catch this, this afaict should be a
> >    tested scenario
> > 4) Fix confusing variable naming around newSlot/newslot in ExecBRUpdateTriggers
> 
> Maybe instead of 1+2, change ExecCopySlot like this:
> 
> -    dstslot->tts_ops->copyslot(dstslot, srcslot);
> +    if (dstslot != srcslot)
> +        dstslot->tts_ops->copyslot(dstslot, srcslot);
> 
> That would fix other similar instances, not just this one caller.

Yea, I was wondering about that too - but asking for a slot to be copied
into itself seems to indicate a logic bug more often than not? Expecting
the slots to be independent, afterwards. So I'm a bit hesitant doing so.

Greetings,

Andres Freund