Commit 337cebbd authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
Browse files

mptcp: really cope with fastopen race 



Fastopen and PM-trigger subflow shutdown can race, as reported by
syzkaller.

In my first attempt to close such race, I missed the fact that
the subflow status can change again before the subflow_state_change
callback is invoked.

Address the issue additionally copying with all the states directly
reachable from TCP_FIN_WAIT1.

Fixes: 1e777f39 ("mptcp: add MSG_FASTOPEN sendmsg flag support")
Fixes: 4fd19a30 ("mptcp: fix inconsistent state on fastopen race")
Cc: stable@vger.kernel.org
Reported-by: default avatar <syzbot+c53d4d3ddb327e80bc51@syzkaller.appspotmail.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/458


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Reviewed-by: default avatarMat Martineau <martineau@kernel.org>
Signed-off-by: default avatarMatthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f012d796

net/mptcp/protocol.h

+2 −1
Original line number Diff line number Diff line
@@ -1129,7 +1129,8 @@ static inline bool subflow_simultaneous_connect(struct sock *sk) 
{

	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);



	return (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_FIN_WAIT1) &&

	return (1 << sk->sk_state) &

	       (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2 | TCPF_CLOSING) &&

	       is_active_ssk(subflow) &&

	       !subflow->conn_finished;

}