[Dovecot] memory allocation issues

[Timo Sirainen]

On 9.11.2012, at 2.49, Kelsey Cummings wrote:

> One of our dovecot backend servers ran into a problem with it's auth
> process a few days ago.  This doesn't appear to be the error logged when
> dovecot hits its internal limit so I'm not sure what is going on here.
> 
> auth: Error: malloc: 58012: Cannot allocate memory
> auth: Error: Unable to allocate memory for mutexes from the region
> auth: Error: PANIC: Cannot allocate memory
> auth: passwd(test,1.1.1.1,<8HTlNHzNIQBAjhKC>): unknown user

It would have been nicer if libc would have just crashed the process instead of silently converting it into "unknown user" error.. That's probably actually a bug since the getpwuid_r() that Dovecot uses would have been able to return an error message.

> pop3: Error: Authenticated user not found from userdb, auth lookup +id=2509111297 (client-pid=4781 client-id=1)
> pop3-login: Internal login failure (pid=4781 id=1) (internal failure, 1 +succesful auths): user=<test>...
> 
> There was at least 10+GB free RAM on the server and no indication of a
> system level issue at the same time.  The server is running 2.1.9.
> There were about 3,200 active sessions, with something like 12 new
> sessions/sec.  The other identical servers are/were handling virtually
> identical load with the same service uptime and haven't had any issues 
> so far.  (Crash happened 7 days ago.)

Memory leak maybe? service auth { vsz_limit } anyway was reached (default 256 MB).