Re: 9.4 beta1 crash on Debian sid/i386

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andres Freund <andres(at)2ndquadrant(dot)com>
Cc: Christoph Berg <cb(at)df7cb(dot)de>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: 9.4 beta1 crash on Debian sid/i386
Date: 2014-05-18 21:56:48
Message-ID: 26945.1400450208@sss.pgh.pa.us
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Andres Freund <andres(at)2ndquadrant(dot)com> writes:
> On 2014-05-18 17:41:17 -0400, Tom Lane wrote:
>> OK, so the problem is that getrlimit(RLIMIT_STACK) is lying to us about
>> the available stack depth. I'd classify that as a kernel bug. I wonder
>> if it's a different manifestation of this issue:
>> https://bugzilla.redhat.com/show_bug.cgi?id=952946

> That'd explain why I couldn't reproduce it. And I seme to recall some
> messages about the hardening stuff in debian accidentally being lost
> some time ago. So if that got re-introduced into 9.4... The CFLAGS
> certainly indicate that -pie is getting used.

Yeah. Re-reading the Red Hat bug, it seems like an exact match for
this issue. The dependency on ASLR means that the identical run
might sometimes work and sometimes crash, which would explain why
Christoph was getting less-than-consistent results.

The bad news is that the kernel guys have been ignoring the issue
for over a year. Dunno if some pressure from the Debian camp would
help raise their priority for this.

regards, tom lane

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