On Mon, Aug 26, 2019 at 1:44 PM Justin Pryzby <pryzby@telsasoft.com> wrote:
> On Mon, Aug 26, 2019 at 01:09:19PM +1200, Thomas Munro wrote:
> > On Sun, Aug 25, 2019 at 3:15 PM Peter Geoghegan <pg@bowt.ie> wrote:
> > > I was reminded of this issue from last year, which also appeared to
> > > involve BufFileClose() and a double-free:
> > >
> > > https://postgr.es/m/87y3hmee19.fsf@news-spur.riddles.org.uk
> > >
> > > That was a BufFile that was under the control of a tuplestore, so it
> > > was similar to but different from your case. I suspect it's related.
> >
> > Hmm. tuplestore.c follows the same coding pattern as nodeHashjoin.c:
> > it always nukes its pointer after calling BufFileFlush(), so it
> > shouldn't be capable of calling it twice for the same pointer, unless
> > we have two copies of that pointer somehow.
> >
> > Merlin's reported a double-free apparently in ExecHashJoin(), not
> > ExecHashJoinNewBatch() like this report. Unfortunately that tells us
> > very little.
Here's another one:
https://www.postgresql.org/message-id/flat/20170601081104.1500.56202%40wrigleys.postgresql.org
Hmm. Also on RHEL/CentOS 6, and also involving sorting, hashing,
BufFileClose() but this time the glibc double free error is in
repalloc().
And another one (repeatedly happening):
https://www.postgresql.org/message-id/flat/3976998C-8D3B-4825-9B10-69ECB70A597A%40appnexus.com
Also on RHEL/CentOS 6, this time a sort in once case and a hash join
in another case.
Of course it's entirely possible that we have a bug here and I'm very
keen to find it, but I can't help noticing the common factor here is
that they're all running ancient RHEL 6.x releases, except Merlin who
didn't say. Merlin?
--
Thomas Munro
https://enterprisedb.com