netdev - Re: UNIX sockets kernel panic

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Message-Id: <20081105.171822.193705306.davem@davemloft.net>
Date:	Wed, 05 Nov 2008 17:18:22 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	adobriyan@...il.com
Cc:	netdev@...r.kernel.org, a.bittau@...ucl.ac.uk
Subject: Re: UNIX sockets kernel panic

From: Alexey Dobriyan <adobriyan@...il.com>
Date: Thu, 6 Nov 2008 04:13:19 +0300

> On Thu, Nov 06, 2008 at 12:14:46AM +0000, Andrea Bittau wrote:
> > The following code causes a kernel panic on Linux 2.6.26:
> > http://darkircop.org/unix.c
> > 
> > I haven't investigated the bug so I'm not sure what is causing it, and
> > don't know if it's exploitable.  The code passes unix sockets from one
> > process to another using unix sockets.  The bug probably has to do with
> > closing file descriptors.
> 
> Aie, nice localhost DoS (random oopses)

Indeed.  I'm looking at it too and in my case I get random memory
corruption, usually it's skb->destruct being set to garbage and then
we hit the WARN_ON(in_irq()) in net/core/skbuff.c

I think the key is passing a unix socket fd (as opposed to some other
kind of fd) using SCM_RIGHTS and the ordering of the fd closes.
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