This is a note to let you know that I've just added the patch titled
mptcp: ensure listener is unhashed before updating the sk status
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mptcp-ensure-listener-is-unhashed-before-updating-the-sk-status.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 57fc0f1ceaa4016354cf6f88533e20b56190e41a Mon Sep 17 00:00:00 2001
From: Paolo Abeni <pabeni@xxxxxxxxxx>
Date: Tue, 20 Jun 2023 18:24:23 +0200
Subject: mptcp: ensure listener is unhashed before updating the sk status
From: Paolo Abeni <pabeni@xxxxxxxxxx>
commit 57fc0f1ceaa4016354cf6f88533e20b56190e41a upstream.
The MPTCP protocol access the listener subflow in a lockless
manner in a couple of places (poll, diag). That works only if
the msk itself leaves the listener status only after that the
subflow itself has been closed/disconnected. Otherwise we risk
deadlock in diag, as reported by Christoph.
Address the issue ensuring that the first subflow (the listener
one) is always disconnected before updating the msk socket status.
Reported-by: Christoph Paasch <cpaasch@xxxxxxxxx>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/407
Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Reviewed-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
Signed-off-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/mptcp/pm_netlink.c | 1 +
net/mptcp/protocol.c | 31 +++++++++++++++++++------------
2 files changed, 20 insertions(+), 12 deletions(-)
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -1047,6 +1047,7 @@ static int mptcp_pm_nl_create_listen_soc
if (err)
return err;
+ inet_sk_state_store(newsk, TCP_LISTEN);
err = kernel_listen(ssock, backlog);
if (err)
return err;
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2385,13 +2385,6 @@ static void __mptcp_close_ssk(struct soc
kfree_rcu(subflow, rcu);
} else {
/* otherwise tcp will dispose of the ssk and subflow ctx */
- if (ssk->sk_state == TCP_LISTEN) {
- tcp_set_state(ssk, TCP_CLOSE);
- mptcp_subflow_queue_clean(sk, ssk);
- inet_csk_listen_stop(ssk);
- mptcp_event_pm_listener(ssk, MPTCP_EVENT_LISTENER_CLOSED);
- }
-
__tcp_close(ssk, 0);
/* close acquired an extra ref */
@@ -2926,10 +2919,24 @@ static __poll_t mptcp_check_readable(str
return EPOLLIN | EPOLLRDNORM;
}
-static void mptcp_listen_inuse_dec(struct sock *sk)
+static void mptcp_check_listen_stop(struct sock *sk)
{
- if (inet_sk_state_load(sk) == TCP_LISTEN)
- sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
+ struct sock *ssk;
+
+ if (inet_sk_state_load(sk) != TCP_LISTEN)
+ return;
+
+ sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
+ ssk = mptcp_sk(sk)->first;
+ if (WARN_ON_ONCE(!ssk || inet_sk_state_load(ssk) != TCP_LISTEN))
+ return;
+
+ lock_sock_nested(ssk, SINGLE_DEPTH_NESTING);
+ mptcp_subflow_queue_clean(sk, ssk);
+ inet_csk_listen_stop(ssk);
+ mptcp_event_pm_listener(ssk, MPTCP_EVENT_LISTENER_CLOSED);
+ tcp_set_state(ssk, TCP_CLOSE);
+ release_sock(ssk);
}
bool __mptcp_close(struct sock *sk, long timeout)
@@ -2942,7 +2949,7 @@ bool __mptcp_close(struct sock *sk, long
WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK);
if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) {
- mptcp_listen_inuse_dec(sk);
+ mptcp_check_listen_stop(sk);
inet_sk_state_store(sk, TCP_CLOSE);
goto cleanup;
}
@@ -3056,7 +3063,7 @@ static int mptcp_disconnect(struct sock
if (msk->fastopening)
return -EBUSY;
- mptcp_listen_inuse_dec(sk);
+ mptcp_check_listen_stop(sk);
inet_sk_state_store(sk, TCP_CLOSE);
mptcp_stop_timer(sk);
Patches currently in stable-queue which might be from pabeni@xxxxxxxxxx are
queue-6.3/mptcp-consolidate-fallback-and-non-fallback-state-machine.patch
queue-6.3/mptcp-fix-possible-divide-by-zero-in-recvmsg.patch
queue-6.3/mptcp-ensure-listener-is-unhashed-before-updating-the-sk-status.patch
queue-6.3/selftests-mptcp-remove-duplicated-entries-in-usage.patch
queue-6.3/mptcp-fix-possible-list-corruption-on-passive-mpj.patch
queue-6.3/mptcp-handle-correctly-disconnect-failures.patch
