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

From: Eric Dumazet <redacted>
Date: Mon, 14 Aug 2017 17:44:43 -0700

From: Eric Dumazet <redacted>

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 <redacted>
Reported-by: Dmitry Vyukov <dvyukov@google.com>

Applied, thanks.