From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
---|---|
To: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
Cc: | Andres Freund <andres(at)anarazel(dot)de>, "Vitaly V(dot) Voronov" <wizard_1024(at)tut(dot)by>, PostgreSQL mailing lists <pgsql-bugs(at)lists(dot)postgresql(dot)org> |
Subject: | Re: BUG #15144: *** glibc detected *** postgres: postgres smsconsole [local] SELECT: double free or corruption (!pre |
Date: | 2018-04-16 18:03:04 |
Message-ID: | CAH2-Wz=RDFQAqczdFezYCuyEHid4eHe6e5uEu1cVsFg7t4Hsyw@mail.gmail.com |
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On Mon, Apr 16, 2018 at 10:48 AM, Alvaro Herrera
<alvherre(at)alvh(dot)no-ip(dot)org> wrote:
> and tuplestore_end does this:
> if (state->myfile)
> BufFileClose(state->myfile);
> without setting anything in state to NULL; so we're relying on the
> caller fs->tstore to null to avoid repeated tuplestore_end calls. I
> can't see any way for this to misbehave, but maybe the funcstate appears
> more than once in the PerFuncState array, and we clean it correctly the
> first time around and then invoke the tuplestore_end() the second time
> to the memory that was previously freed? I think this makes no sense
> unless we share FunctionScanPerFuncState elements -- do we?
I have no reason to think that we do. Offhand, I find it more likely
that some executor slot that imagines that it owns the tuple frees the
tuple once, which is followed by a call to tuplestore_end() that frees
the same tuple a second time (a double-free). As I mentioned, we've
seen several bugs of that general variety in both tuplestore and
tuplesort in the past. Some of these have been very subtle.
Note that pgpool is involved here. I don't know much about pgpool, and
maybe that's totally irrelevant.
--
Peter Geoghegan
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