From: Willem de Bruijn <willemdebruijn.ker...@gmail.com>
Date: Tue, 26 Sep 2017 12:19:37 -0400
> From: Willem de Bruijn <will...@google.com>
>
> Once a socket has po->fanout set, it remains a member of the group
> until it is destroyed. The prot_hook must be constant and identical
> across sockets in the group.
>
> If fanout_add races with packet_do_bind between the test of po->fanout
> and taking the lock, the bind call may make type or dev inconsistent
> with that of the fanout group.
>
> Hold po->bind_lock when testing po->fanout to avoid this race.
>
> I had to introduce artificial delay (local_bh_enable) to actually
> observe the race.
>
> Fixes: dc99f600698d ("packet: Add fanout support.")
> Signed-off-by: Willem de Bruijn <will...@google.com>
> Reviewed-by: Eric Dumazet <eduma...@google.com>
Applied and queued up for -stable.
