mptcp: do not fallback when OoO is present

commit 1bba3f219c5e8c29e63afa3c1fc24f875ebec119 upstream.

In case of DSS corruption, the MPTCP protocol tries to avoid the subflow
reset if fallback is possible. Such corruptions happen in the receive
path; to ensure fallback is possible the stack additionally needs to
check for OoO data, otherwise the fallback will break the data stream.

Fixes: e32d262c89e2 ("mptcp: handle consistently DSS corruption")
Cc: stable@vger.kernel.org
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/598
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20251118-net-mptcp-misc-fixes-6-18-rc6-v1-4-806d3781c95f@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Paolo Abeni
2025-11-18 08:20:22 +01:00
committed by Greg Kroah-Hartman
parent 8a5d1ceef9
commit 642561238c

View File

@@ -904,6 +904,13 @@ static bool __mptcp_finish_join(struct mptcp_sock *msk, struct sock *ssk)
if (sk->sk_state != TCP_ESTABLISHED)
return false;
/* The caller possibly is not holding the msk socket lock, but
* in the fallback case only the current subflow is touching
* the OoO queue.
*/
if (!RB_EMPTY_ROOT(&msk->out_of_order_queue))
return false;
spin_lock_bh(&msk->fallback_lock);
if (!msk->allow_subflows) {
spin_unlock_bh(&msk->fallback_lock);