A Debian user has accidentally uncovered a problem with the passdb code: if the 'passdb backend' list is explicity set to an empty string in smb.conf, smbd will segfault whenever an incoming connection attempt is received. This is certainly a meaningless configuration, but Samba should handle it more gracefully; at a minimum, by throwing a comprehensible error to the logs when it happens and throwing a warning in testparm, or possibly by treating an empty string as equivalent to the default backend list.
It will now spit out a level 0 debug when it is encountered, and testparm will warn the users. I chose not to have it default instead, because this is already an advanced option, and this would actually muck up the loadparm logic a bit. It is handled as any other string parm, and an empty string is a valid parm. It does not segfault anymore, but the user will get an access denied (because smbd has no idea who it is).
originally reported against 3.0aph24. Bugzilla spring cleaning. Removing old alpha versions.
sorry for the same, cleaning up the database to prevent unecessary reopens of bugs.