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.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x d82809b6c5f2676b382f77a5cbeb1a5d91ed2235 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024083029-shrank-thirstily-a532@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

d82809b6c5f2 ("mptcp: avoid duplicated SUB_CLOSED events") a7cfe7766370 ("mptcp: fix data races on local_id") 84c531f54ad9 ("mptcp: userspace pm send RM_ADDR for ID 0") f1f26512a9bf ("mptcp: use plain bool instead of custom binary enum") 1e07938e29c5 ("net: mptcp: rename netlink handlers to mptcp_pm_nl_<blah>_{doit,dumpit}") 1d0507f46843 ("net: mptcp: convert netlink from small_ops to ops") fce68b03086f ("mptcp: add scheduled in mptcp_subflow_context") 1730b2b2c5a5 ("mptcp: add sched in mptcp_sock") 740ebe35bd3f ("mptcp: add struct mptcp_sched_ops") a7384f391875 ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net")

thanks,

greg k-h

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

From d82809b6c5f2676b382f77a5cbeb1a5d91ed2235 Mon Sep 17 00:00:00 2001 From: "Matthieu Baerts (NGI0)" matttbe@kernel.org Date: Wed, 28 Aug 2024 08:14:35 +0200 Subject: [PATCH] mptcp: avoid duplicated SUB_CLOSED events MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

The initial subflow might have already been closed, but still in the connection list. When the worker is instructed to close the subflows that have been marked as closed, it might then try to close the initial subflow again.

A consequence of that is that the SUB_CLOSED event can be seen twice:

# ip mptcp endpoint 1.1.1.1 id 1 subflow dev eth0 2.2.2.2 id 2 subflow dev eth1

# ip mptcp monitor & [ CREATED] remid=0 locid=0 saddr4=1.1.1.1 daddr4=9.9.9.9 [ ESTABLISHED] remid=0 locid=0 saddr4=1.1.1.1 daddr4=9.9.9.9 [ SF_ESTABLISHED] remid=0 locid=2 saddr4=2.2.2.2 daddr4=9.9.9.9

# ip mptcp endpoint delete id 1 [ SF_CLOSED] remid=0 locid=0 saddr4=1.1.1.1 daddr4=9.9.9.9 [ SF_CLOSED] remid=0 locid=0 saddr4=1.1.1.1 daddr4=9.9.9.9

The first one is coming from mptcp_pm_nl_rm_subflow_received(), and the second one from __mptcp_close_subflow().

To avoid doing the post-closed processing twice, the subflow is now marked as closed the first time.

Note that it is not enough to check if we are dealing with the first subflow and check its sk_state: the subflow might have been reset or closed before calling mptcp_close_ssk().

Fixes: b911c97c7dc7 ("mptcp: add netlink event support") Cc: stable@vger.kernel.org Tested-by: Arınç ÜNAL arinc.unal@arinc9.com Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index b571fba88a2f..37ebcb7640eb 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2508,6 +2508,12 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk, 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) + return; + + subflow->close_event_done = true; + if (sk->sk_state == TCP_ESTABLISHED) mptcp_event(MPTCP_EVENT_SUB_CLOSED, mptcp_sk(sk), ssk, GFP_KERNEL);

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 240d7c2ea551..26eb898a202b 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -524,7 +524,8 @@ struct mptcp_subflow_context { stale : 1, /* unable to snd/rcv data, do not use for xmit */ valid_csum_seen : 1, /* at least one csum validated */ is_mptfo : 1, /* subflow is doing TFO */ - __unused : 10; + close_event_done : 1, /* has done the post-closed part */ + __unused : 9; bool data_avail; bool scheduled; u32 remote_nonce;