Panic/Assert dns-lookup.c

[tim at linux-daus.de]

> Aki Tuomi <aki.tuomi at open-xchange.com> hat am 30. März 2020 17:39 geschrieben:
>  
> > On 30/03/2020 18:32 tim at linux-daus.de wrote:
> > 
> > > Aki Tuomi <aki.tuomi at open-xchange.com> hat am 30. März 2020 16:23 geschrieben:
> > >
> > > Can you install dovecot-dbg to get debug symbols, open the core in gdb and run 
> > > 
> > > bt full
> > > 
> > 
> > Full backtrace:
> > 
> 
> <snip />
> 
> It seems that your configuration ends up passing empty host from the user lookup to DNS resolve. This should be handled earlier of course, if this is really the case.
> 
> Do you have any idea which user is triggering this based on logs? You could try 'doveadm auth lookup <username>' to see if you are getting bad values? Are you able to turn on 'auth_debug=yes', I understand it might be high volume with 7k logins.

Thanks for the hint! We were able to identify a user with a look in the core dump and i think we were able to find the issue. Some user try to authenticate with an "alias user" which typically missing the mailbox host information. Currently we do some test to verify the issue. If it is so we will modify the database lookups to prevent this circumstances.

Tim