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

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Message-Id: <20151116.154009.530996237690972616.davem@davemloft.net>
Date:	Mon, 16 Nov 2015 15:40:09 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	hannes@...essinduktion.org
Cc:	netdev@...r.kernel.org, dvyukov@...gle.com, eric.dumazet@...il.com
Subject: Re: [PATCH net] af_unix: don't append consumed skbs to
 sk_receive_queue

From: Hannes Frederic Sowa <hannes@...essinduktion.org>
Date: Mon, 16 Nov 2015 16:25:56 +0100

> 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>

Applied and queued up for -stable, thanks.
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