netdev - Re: [PATCH net] tcp: fix possible deadlock in TCP stack vs BPF filter

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Message-Id: <20170814.223219.1520974525933260255.davem@davemloft.net>
Date:   Mon, 14 Aug 2017 22:32:19 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     eric.dumazet@...il.com
Cc:     netdev@...r.kernel.org, fengc@...gle.com
Subject: Re: [PATCH net] tcp: fix possible deadlock in TCP stack vs BPF
 filter

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Mon, 14 Aug 2017 17:44:43 -0700

> From: Eric Dumazet <edumazet@...gle.com>
> 
> Filtering the ACK packet was not put at the right place.
> 
> At this place, we already allocated a child and put it
> into accept queue.
> 
> We absolutely need to call tcp_child_process() to release
> its spinlock, or we will deadlock at accept() or close() time.
> 
> Found by syzkaller team (Thanks a lot !)
> 
> Fixes: 8fac365f63c8 ("tcp: Add a tcp_filter hook before handle ack packet")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: Dmitry Vyukov <dvyukov@...gle.com>

Applied, thanks.