tcp: fix possible deadlock in TCP stack vs BPF filter
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 at google.com>
Reported-by: Dmitry Vyukov <dvyukov at google.com>
Cc: Chenbo Feng <fengc at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
UnifiedSplitRaw
