From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH net-next] tcp: fix hang in tcp_sendpage_locked()
Date: Fri, 25 Aug 2017 17:22:41 -0700 (PDT)
Message-ID: <20170825.172241.418919299899603346.davem@davemloft.net>
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Cc: netdev@vger.kernel.org, tom@quantonium.net, dvyukov@google.com
To: eric.dumazet@gmail.com
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From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 25 Aug 2017 06:27:05 -0700

> From: Eric Dumazet <edumazet@google.com>
> 
> syszkaller got a hang in tcp stack, related to a bug in
> tcp_sendpage_locked()
> 
> root@syzkaller:~# cat /proc/3059/stack
> [<ffffffff83de926c>] __lock_sock+0x1dc/0x2f0
> [<ffffffff83de9473>] lock_sock_nested+0xf3/0x110
> [<ffffffff8408ce01>] tcp_sendmsg+0x21/0x50
> [<ffffffff84163b6f>] inet_sendmsg+0x11f/0x5e0
> [<ffffffff83dd8eea>] sock_sendmsg+0xca/0x110
> [<ffffffff83dd9547>] kernel_sendmsg+0x47/0x60
> [<ffffffff83de35dc>] sock_no_sendpage+0x1cc/0x280
> [<ffffffff8408916b>] tcp_sendpage_locked+0x10b/0x160
> [<ffffffff84089203>] tcp_sendpage+0x43/0x60
> [<ffffffff841641da>] inet_sendpage+0x1aa/0x660
> [<ffffffff83dd4fcd>] kernel_sendpage+0x8d/0xe0
> [<ffffffff83dd50ac>] sock_sendpage+0x8c/0xc0
> [<ffffffff81b63300>] pipe_to_sendpage+0x290/0x3b0
> [<ffffffff81b67243>] __splice_from_pipe+0x343/0x750
> [<ffffffff81b6a459>] splice_from_pipe+0x1e9/0x330
> [<ffffffff81b6a5e0>] generic_splice_sendpage+0x40/0x50
> [<ffffffff81b6b1d7>] SyS_splice+0x7b7/0x1610
> [<ffffffff84d77a01>] entry_SYSCALL_64_fastpath+0x1f/0xbe
> 
> Fixes: 306b13eb3cf9 ("proto_ops: Add locked held versions of sendmsg and sendpage")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Dmitry Vyukov <dvyukov@google.com>

APplied, thanks Eric.