The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Possible dependencies:

d4e85922e3e7 ("mptcp: do not wait for bare sockets' timeout") 76a13b315709 ("mptcp: invoke MP_FAIL response when needed") d9fb797046c5 ("mptcp: Do not traverse the subflow connection list without lock") d42f9e4e2384 ("mptcp: Check for orphaned subflow before handling MP_FAIL timer") d7e6f5836038 ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d4e85922e3e7ef2071f91f65e61629b60f3a9cf4 Mon Sep 17 00:00:00 2001 From: Paolo Abeni pabeni@redhat.com Date: Tue, 7 Feb 2023 14:04:13 +0100 Subject: [PATCH] mptcp: do not wait for bare sockets' timeout

If the peer closes all the existing subflows for a given mptcp socket and later the application closes it, the current implementation let it survive until the timewait timeout expires.

While the above is allowed by the protocol specification it consumes resources for almost no reason and additionally causes sporadic self-tests failures.

Let's move the mptcp socket to the TCP_CLOSE state when there are no alive subflows at close time, so that the allocated resources will be freed immediately.

Fixes: e16163b6e2b7 ("mptcp: refactor shutdown and close") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Matthieu Baerts matthieu.baerts@tessares.net Signed-off-by: Matthieu Baerts matthieu.baerts@tessares.net Signed-off-by: David S. Miller davem@davemloft.net

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 8cd6cc67c2c5..bc6c1f62a690 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2897,6 +2897,7 @@ bool __mptcp_close(struct sock *sk, long timeout) struct mptcp_subflow_context *subflow; struct mptcp_sock *msk = mptcp_sk(sk); bool do_cancel_work = false; + int subflows_alive = 0;

sk->sk_shutdown = SHUTDOWN_MASK;

@@ -2922,6 +2923,8 @@ bool __mptcp_close(struct sock *sk, long timeout) struct sock *ssk = mptcp_subflow_tcp_sock(subflow); bool slow = lock_sock_fast_nested(ssk);

+ subflows_alive += ssk->sk_state != TCP_CLOSE; + /* since the close timeout takes precedence on the fail one, * cancel the latter */ @@ -2937,6 +2940,12 @@ bool __mptcp_close(struct sock *sk, long timeout) } sock_orphan(sk);

+ /* all the subflows are closed, only timeout can change the msk + * state, let's not keep resources busy for no reasons + */ + if (subflows_alive == 0) + inet_sk_state_store(sk, TCP_CLOSE); + sock_hold(sk); pr_debug("msk=%p state=%d", sk, sk->sk_state); if (msk->token)