netdev - Re: [PATCH net] af_unix: don't append consumed skbs to sk_receive

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Message-ID: <1447691880.22599.68.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Mon, 16 Nov 2015 08:38:00 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc:	netdev@...r.kernel.org, Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH net] af_unix: don't append consumed skbs to
 sk_receive_queue

On Mon, 2015-11-16 at 16:25 +0100, Hannes Frederic Sowa wrote:
> In case multiple writes to a unix stream socket race we could end up in a
> situation where we pre-allocate a new skb for use in unix_stream_sendpage
> but have to free it again in the locked section because another skb
> has been appended meanwhile, which we must use. Accidentally we didn't
> clear the pointer after consuming it and so we touched freed memory
> while appending it to the sk_receive_queue. So, clear the pointer after
> consuming the skb.
> 
> This bug has been found with syzkaller
> (http://github.com/google/syzkaller) by Dmitry Vyukov.
> 
> Fixes: 869e7c62486e ("net: af_unix: implement stream sendpage support")
> Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
> Cc: Dmitry Vyukov <dvyukov@...gle.com>
> Cc: Eric Dumazet <eric.dumazet@...il.com>
> Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
> ---

Acked-by: Eric Dumazet <edumazet@...gle.com>


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