[Dovecot] Imap segfault on login with version 2.0.8 & 2.0.11

[Nicholas VonHollen]

"Timo Sirainen" <tss at iki.fi> said:

> On 8.4.2011, at 0.17, Nicholas VonHollen wrote:
> 
>> Thanks for helping me out.  It looks like no matter what I do, changing the
>> executable line doesn't help.  I even changed it to "executable = /bin/false" and
>> it still reports a segfault.  I verified the config with "dovecot -n", stopped
>> using the "-c /etc/dovecot.conf", moved the conf file to the appropriate place,
>> re-verified it, and I still can't affect it.  I assume the crash is happening
>> post-fork, pre-exec, if there is custom code for launching child processes. 
>> Since strace 'fixes' the problem, I'll try to figure it out under gdb, but to be
>> honest, my C debugging skills are very rusty.
> 
> Ah, yes:
> 
>> Apr  7 17:29:05 localhost dovecot: master: Error: service(imap): child 9690
>> killed with signal 11 (core dumps disabled)
> 
> It has "master:" prefix so it's pre-exec. But you got a core file earlier, right?
> You should be able to get a usable gdb backtrace then with "gdb dovecot core".
> 


GDB still complains "warning: core file may not match specified executable file." when using anything but /bin/false.  I tried using "gdb dovecot corefile" but got the same trace with nothing but _start.  Is it possible to crash post-exec and pre-main?  I'm not sure that makes sense, lol.  You can't really pass pointers to child processes, so maybe ld is somehow screwed up?  I can try it on a different OS with a similar RPM.



Nick VonHollen
Rackspace Software Developer
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