netdev - Re: [PATCH net] tcp: purge write queue in tcp_connect

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Message-Id: <20180516.121909.2062726910814553634.davem@davemloft.net>
Date:   Wed, 16 May 2018 12:19:09 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     edumazet@...gle.com
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com, ycheng@...gle.com,
        ncardwell@...gle.com
Subject: Re: [PATCH net] tcp: purge write queue in tcp_connect_init()

From: Eric Dumazet <edumazet@...gle.com>
Date: Mon, 14 May 2018 21:14:26 -0700

> syzkaller found a reliable way to crash the host, hitting a BUG()
> in __tcp_retransmit_skb()
> 
> Malicous MSG_FASTOPEN is the root cause. We need to purge write queue
> in tcp_connect_init() at the point we init snd_una/write_seq.
> 
> This patch also replaces the BUG() by a less intrusive WARN_ON_ONCE()
 ...
> Fixes: cf60af03ca4e ("net-tcp: Fast Open client - sendmsg(MSG_FASTOPEN)")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Yuchung Cheng <ycheng@...gle.com>
> Cc: Neal Cardwell <ncardwell@...gle.com>
> Reported-by: syzbot <syzkaller@...glegroups.com>

Applied and queued up for -stable, thanks Eric.