Crash in timsieved's cmd_authenticate() on 2.4.6

[Florian Pflug]

On Jan12, 2011, at 03:32 , Greg Banks wrote:
> On 12/01/11 02:21, Florian Pflug wrote:
>> If the authenticating user is an admin, we proceed even if the mailbox
>> lookup fails. In this case, the mboxlist_lookup seems to leave the
>> mboxlist_entry uninitialized, making the code believe that the mailbox
>> is remote if the bit MBTYPE_REMOTE happens to be set in mbentry.mvtype.
>> The crash then happens when xstrdup tried to copy mbentry.partition.
>> 
>> Initializing mbentry to zero in cmd_authenticate() fixes the bug and
>> allows admins without mailboxes (like root) to authenticate again
>> on my system.
> 
> Thanks, your analysis is correct, but I think a better fix might be the attached (untested) patch.

That's exactly what I did initially :-)

I didn't like it much, though. The bug was probably introduced precisely
because someone *didn't* realize that mbentry is uninitialized in the 
corner-case of an admin user without a mailbox. Leaving things that way
carries a high risk of a similar bug being re-introduces by the next
one who touches this code.

What about doing both the "!r" check and zero-initializing mbentry?

> Bron changed the mboxlist_lookup() API very recently (not yet in a release), which means that patch won't apply to ToT, but the bug is still there.  As coincidentally I touched that code yesterday, I'll fix it.

Cool, thanks!

best regards,
Florian Pflug