Commit 9f1a9881 authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
Browse files

mptcp: process pending subflow error on close 

On incoming TCP reset, subflow closing could happen before error
propagation. That in turn could cause the socket error being ignored,
and a missing socket state transition, as reported by Daire-Byrne.

Address the issues explicitly checking for subflow socket error at
close time. To avoid code duplication, factor-out of __mptcp_error_report()
a new helper implementing the relevant bits.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/429


Fixes: 15cc1045 ("mptcp: deliver ssk errors to msk")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Reviewed-by: default avatarMat Martineau <martineau@kernel.org>
Signed-off-by: default avatarMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d5fbeff1

net/mptcp/protocol.c

+34 −29
Original line number Diff line number Diff line
@@ -770,24 +770,19 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk) 
	return moved;

}



void __mptcp_error_report(struct sock *sk)

static bool __mptcp_subflow_error_report(struct sock *sk, struct sock *ssk)

{

	struct mptcp_subflow_context *subflow;

	struct mptcp_sock *msk = mptcp_sk(sk);



	mptcp_for_each_subflow(msk, subflow) {

		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);

	int err = sock_error(ssk);

	int ssk_state;



	if (!err)

			continue;

		return false;



	/* only propagate errors on fallen-back sockets or

	 * on MPC connect

	 */

		if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))

			continue;

	if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(mptcp_sk(sk)))

		return false;



	/* We need to propagate only transition to CLOSE state.

	 * Orphaned socket will see such state change via
@@ -802,8 +797,17 @@ void __mptcp_error_report(struct sock *sk) 
	/* This barrier is coupled with smp_rmb() in mptcp_poll() */

	smp_wmb();

	sk_error_report(sk);

		break;

	return true;

}



void __mptcp_error_report(struct sock *sk)

{

	struct mptcp_subflow_context *subflow;

	struct mptcp_sock *msk = mptcp_sk(sk);



	mptcp_for_each_subflow(msk, subflow)

		if (__mptcp_subflow_error_report(sk, mptcp_subflow_tcp_sock(subflow)))

			break;

}



/* In most cases we will be able to lock the mptcp socket.  If its already
@@ -2428,6 +2432,7 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk, 
	}



out_release:

	__mptcp_subflow_error_report(sk, ssk);

	release_sock(ssk);



	sock_put(ssk);