netdev - Re: [PATCH net] tcp: avoid infinite loop in tcp_splice

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Message-Id: <20170206.223936.1614855798292057873.davem@davemloft.net>
Date:   Mon, 06 Feb 2017 22:39:36 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     eric.dumazet@...il.com
Cc:     netdev@...r.kernel.org, w@....eu, dvyukov@...gle.com
Subject: Re: [PATCH net] tcp: avoid infinite loop in tcp_splice_read()

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Fri, 03 Feb 2017 14:59:38 -0800

> From: Eric Dumazet <edumazet@...gle.com>
> 
> Splicing from TCP socket is vulnerable when a packet with URG flag is
> received and stored into receive queue.
> 
> __tcp_splice_read() returns 0, and sk_wait_data() immediately
> returns since there is the problematic skb in queue.
> 
> This is a nice way to burn cpu (aka infinite loop) and trigger
> soft lockups.
> 
> Again, this gem was found by syzkaller tool.
> 
> Fixes: 9c55e01c0cc8 ("[TCP]: Splice receive support.")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: Dmitry Vyukov  <dvyukov@...gle.com>
> Cc: Willy Tarreau <w@....eu>

Applied and queued up for -stable, thanks Eric.