[Dovecot] crash/mem violation in auth_worker + 50G logs in 2.1.7

[Timo Sirainen]

On Sat, 2013-06-08 at 13:27 +0200, Mrten wrote:
> Hi,
> 
> This morning I discovered what seemed to be a deliberate crash in
> auth_worker:
> 
> Jun  7 23:02:09 localhost dovecot: auth-worker: Error: #007Can't read
> dir of '/etc/mysql/conf.d/' (Errcode: 2)
> Jun  7 23:02:09 localhost dovecot: auth-worker: Error: Fatal error in
> defaults handling. Program aborted
> Jun  7 23:02:09 localhost dovecot: auth-worker: Error: *** glibc
> detected *** dovecot/auth worker: waiting for connection: free():
> invalid pointer: 0x00007fffa0863160 ***
..
> /usr/lib/libmysqlclient.so.18(free_defaults+0x4b)[0x7f22d3796e6b]
> Jun  7 23:02:09 localhost dovecot: auth-worker: Error:
> /usr/lib/libmysqlclient.so.18(mysql_read_default_options+0x13c)[0x7f22d377d00c]
> Jun  7 23:02:09 localhost dovecot: auth-worker: Error:
> /usr/lib/libmysqlclient.so.18(mysql_real_connect+0x8e)[0x7f22d377eb4e]

It crashes in mysql_real_connect() internally, which also starts the
whole mysql session. So this is a bug in MySQL library.

> This repeated until I killed dovecot (12 hours later), by then 54GB of
> logs had accumulated. Besides leaving me impressed with the logserver
> :), I was wondering if this is a known problem.
> 
> Shouldn't dovecot recognize that the auth worker is crashing?

Looks like there was a generic problem with how crash during
initialization was handled. This should fix all of them:
http://hg.dovecot.org/dovecot-2.2/rev/754d244b8249

> One more thing, this is (one line from many) from audit.log (I have
> auditd logging audit records)
> 
> type=ANOM_ABEND msg=audit(1370682566.377:3499876): auid=4294967295
> uid=108 gid=115 ses=4294967295 pid=23187 comm="auth" reason="memory
> violation" sig=6
> 
> 108 is the dovecot user, so it probably is related.

Yeah, that's the same abort() crash.