Re: [exim] Spurious segfaults with Exim 4.88

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Autor: Christian Balzer
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Dla: exim-users
CC: Jeremy Harris
Temat: Re: [exim] Spurious segfaults with Exim 4.88

Hello,

On Wed, 25 Jan 2017 09:34:39 +0000 Jeremy Harris wrote:

> On 25/01/17 07:10, Christian Balzer wrote:
> > I'd be happy to collect cores if this can be turned on with the existing
> > binaries, but I have a feeling that the RLIMIT_CORE override is still in
> > there and not changeable w/o compiling stuff, right?
>
> I'd love a core (even just the stacktrace, though bonus for having
> library -debug packages installed).

Installing those is not an issue.

>I've never had an issue getting
> cores on Fedora or Centos; you do need to check
>
> - ulimit -c


Well, exim doesn't pick that up from the environment it's started from, it
sets that to 0 internally. 
Alas this is Jessie, where the gods have finally blessed us with prlimit
so:
---
# ps faxvww |grep exim
10341 ?        Ss     6:51      0  1093 103138 4924  0.0 /usr/sbin/exim4 -bd -q15s
 4173 ?        S      0:00      0  1093 103374 8748  0.1  \_ /usr/sbin/exim4 -bd -q15s
[...]
# prlimit --pid 10341 |grep core
CORE       max core file size                         0 unlimited blocks
# prlimit --pid 10341 --core=unlimited
# prlimit --pid 10341 |grep core
CORE       max core file size                 unlimited unlimited blocks
---


This is being picked up by the child processes as well.
Alas no cores were forthcoming (in /var/spool/exim4/).

> - /proc/sys/fs/suid_dumpable

That resulted in:
---
Jan 26 00:26:59 mx09 kernel: [9635416.967425] Unsafe core_pattern used with suid_dumpable=2. Pipe handler or fully qualified core dump path required.
---

Fair enough, so setting:

> - /proc/sys/kernel/core_pattern
>

to:
---
# cat /proc/sys/kernel/core_pattern
/var/tmp/core.%e.%p.%h.%t
---
Silenced the warning but still gave me a load of silence.

Cores are hard, lets go shopping?

Christian
-- 
Christian Balzer        Network/Systems Engineer                
chibi@???       Global OnLine Japan/Rakuten Communications
http://www.gol.com/