[Dovecot] A few rc17 imap crashes

[Timo Sirainen]

On Thu, 2007-01-11 at 21:32 +0000, Chris Wakelin wrote:
> > dovecot: Jan 11 11:39:59 Info: IMAP 5751 xxxxxxxx xxx.xxx.xxx.xxx : Opened Sent (18 msgs)
> > dovecot: Jan 11 11:39:59 Error: child 5751 (imap) killed with signal 11
> 
> > dovecot: Jan 11 12:28:49 Info: IMAP 12765 xxxxxxxx xxx.xxx.xxx.xxx : Disconnected: Internal error occurred. Refer to server log for more information. [2007-01-11 12:28:49]
> > dovecot: Jan 11 12:28:49 Error: child 12765 (imap) killed with signal 10

Didn't it log the internal error?

> > #0  0xff1c2838 in t_delete () from /usr/lib/libc.so.1
> > #1  0xff1c23e4 in realfree () from /usr/lib/libc.so.1
> > #2  0xff1c1f48 in _malloc_unlocked () from /usr/lib/libc.so.1
..
> > #0  0xff1c27f0 in t_delete () from /usr/lib/libc.so.1
> > #1  0xff1c23e4 in realfree () from /usr/lib/libc.so.1
..
> > #0  0xff1c2838 in t_delete () from /usr/lib/libc.so.1
> > #1  0xff1c23e4 in realfree () from /usr/lib/libc.so.1
..
> > #0  0xff1c2974 in t_splay () from /usr/lib/libc.so.1
> > #1  0xff1c27e0 in t_delete () from /usr/lib/libc.so.1
> > #2  0xff1c23e4 in realfree () from /usr/lib/libc.so.1
..

These are all from malloc/free, which means there's memory corruption,
which is bad. :( It can't really be debugged from the backtraces, since
the actual bug could have occurred long before it crashed.

Do these happen for different users or only for a couple of users? Do
the crashed users have unusually large mailboxes?

Could you run Dovecot with this:
http://dovecot.org/patches/debug/memdebug-bof.diff
I don't think it'll affect performance much. Only the imap binary needs
to be compiled with it.

There's also this patch:
http://dovecot.org/patches/debug/memdebug-delayed.diff
But it does hurt performance and probably makes Dovecot use a lot more
memory, so it's useful only if you can run it only for a couple of users
who have crashing problems (make mail_executable to be a script which
checks the username and based on that executes different imap binary).
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