mail_crypt crashing randomly during LMTP

[Andi Krischer]

On 29. Mar 2020, at 16:07, Timo Sirainen <timo at sirainen.com> wrote:
> 
> On 29. Mar 2020, at 15.15, Andi Krischer <ak at michaelpelzer.de> wrote:
>> We have a really strange bug with our dovecot setup. After weeks and month of debugging we’re finally reached the point when we ask you for help.
>> 
>> Our basic setup is quite simple: a single dovecot 2.3.10 (0da0eff44) install on Debian 10 with LDAP as user/passdb and sieve, imap_sieve and mail_crypt as mail_plugins.
> 
> Was this happening with old Dovecot versions, or did it start after v2.3.10 upgrade?

Yes, we implemented this setup with v2.3.5.1 on Debian 9 and had the issue right from the beginning.


>> This is what the log says in the moment of crashing:
>> dovecot: lmtp(53852): Panic: Module context mail_crypt_user_module missing
>> *** backtrace *** (see: https://pastebin.com/YCiFtxmy)
> 
> It shows mailbox_free() in the backtrace, so it's probably crashing in mail_crypt_mailbox_close()'s MAIL_CRYPT_CONTEXT(box). But looking at the code, I can't see how that could be possible. Maybe there is some kind of memory corruption or something.
> 
>> dovecot: lmtp(53852): Fatal: master: service(lmtp): child 53852 killed with signal 6 (core dumps disabled - https://dovecot.org/bugreport.html#coredumps)
> 
> Could you get core dumps enabled? See the link. And from the core dump send at least:
> 
> bt full
> fr 6 (or maybe 5 or 7, whichever makes the following command work)
> p *box
> 
> Also please send your doveconf -n output.


Core dump: https://pastebin.com/g4VkMXsT (hope this is everything - I’m not that familiar with core dumps…)

Doveconf: https://pastebin.com/JnhXkYUA

Hope this helps!