From 42c44bd729dcb651ee11de48cfde1e0d5ff0d963 Mon Sep 17 00:00:00 2001 From: "Matthieu Baerts (NGI0)" Date: Tue, 3 Feb 2026 12:50:55 -0500 Subject: [PATCH] mptcp: avoid dup SUB_CLOSED events after disconnect [ Upstream commit 280d654324e33f8e6e3641f76764694c7b64c5db ] In case of subflow disconnect(), which can also happen with the first subflow in case of errors like timeout or reset, mptcp_subflow_ctx_reset will reset most fields from the mptcp_subflow_context structure, including close_event_done. Then, when another subflow is closed, yet another SUB_CLOSED event for the disconnected initial subflow is sent. Because of the previous reset, there are no source address and destination port. A solution is then to also check the subflow's local id: it shouldn't be negative anyway. Another solution would be not to reset subflow->close_event_done at disconnect time, but when reused. But then, probably the whole reset could be done when being reused. Let's not change this logic, similar to TCP with tcp_disconnect(). Fixes: d82809b6c5f2 ("mptcp: avoid duplicated SUB_CLOSED events") Cc: stable@vger.kernel.org Reported-by: Marco Angaroni Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/603 Reviewed-by: Geliang Tang Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260127-net-mptcp-dup-nl-events-v1-1-7f71e1bc4feb@kernel.org Signed-off-by: Jakub Kicinski [ Adjust context ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/mptcp/protocol.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 3cbef3b176a4..f2bf78c019df 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2591,8 +2591,8 @@ out: void mptcp_close_ssk(struct sock *sk, struct sock *ssk, struct mptcp_subflow_context *subflow) { - /* The first subflow can already be closed and still in the list */ - if (subflow->close_event_done) + /* The first subflow can already be closed or disconnected */ + if (subflow->close_event_done || READ_ONCE(subflow->local_id) < 0) return; subflow->close_event_done = true;