netdev - Re: [PATCH v2] [net] af_unix: return data from multiple SKBs on recv() with MSG

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Date:	Sun, 20 Sep 2015 15:38:38 -0400
From:	Aaron Conole <aconole@...heb.org>
To:	Eric Dumazet <eric.dumazet@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH v2] [net] af_unix: return data from multiple SKBs on recv() with MSG_PEEK flag


Resending, I accidentally dropped the list.

> Eric Dumazet <eric.dumazet@...il.com> writes:
>
>> On Sun, 2015-09-20 at 15:07 -0400, Aaron Conole wrote:
>>> Eric Dumazet <eric.dumazet@...il.com> writes:
>>> 
>>> > On Sun, 2015-09-20 at 05:18 -0400, Aaron Conole wrote:
>>> >> From: Aaron Conole <aaron@...heb.org>
>>> >> 
>>> >
>>> > I am wondering what this is expected to do, and how this code would
>>> > possibly not trigger a crash.
>>> Are you suspecting it should crash from a possible double-lock case?
>>> On line 2125, there is an unconditional unlock, which should be 
>>> guaranteeing that there is no longer a condition to 'double lock' the
>>> socket.
>>
>> Not at all.
>>
>> I am suggesting there is a big difference between
>>
>> unix_state_lock(&sk);
>>
>> and
>>
>> unix_state_lock(sk);
>>
>> Can you see it ?

Wow!

That's an excellent catch, thank you! I did test the originally
submitted patch, and got no oops, bug, panic, etc (I usually have
panic_on_oops set to 1 when first testing new code).

I guess I got very lucky, somehow. I'll change this, and make sure
to retest.

I will also try to enhance the python case attached to the bug to
include a filepointer as well, and will repost a v3 when I have done
this.

Thanks,
-Aaron

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html