Merge branch 'mptcp-more-fixes-for-6-3'

Matthieu Baerts says:

====================
mptcp: more fixes for 6.3

Patch 1 avoids scheduling the MPTCP worker on a closed socket on some
edge cases. It fixes issues that can be visible from v5.11.

Patch 2 makes sure the MPTCP worker doesn't try to manipulate
disconnected sockets. This is also a fix for an issue that can be
visible from v5.11.

Patch 3 fixes a NULL pointer dereference when MPTCP FastOpen is used
and an early fallback is done. A fix for v6.2.

Patch 4 improves the stability of the userspace PM selftest for a
subtest added in v6.2.
====================

Link: https://lore.kernel.org/r/20230411-upstream-net-20230411-mptcp-fixes-v1-0-ca540f3ef986@tessares.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

5 files changed, 20 insertions, 18 deletions

diff --git a/net/mptcp/fastopen.c b/net/mptcp/fastopen.c
index d237d142171c5a..bceaab8dd8e460 100644
--- a/net/mptcp/fastopen.c
+++ b/net/mptcp/fastopen.c
@@ -9,11 +9,18 @@
 void mptcp_fastopen_subflow_synack_set_params(struct mptcp_subflow_context *subflow,
 					      struct request_sock *req)
 {
-	struct sock *ssk = subflow->tcp_sock;
-	struct sock *sk = subflow->conn;
+	struct sock *sk, *ssk;
 	struct sk_buff *skb;
 	struct tcp_sock *tp;
 
+	/* on early fallback the subflow context is deleted by
+	 * subflow_syn_recv_sock()
+	 */
+	if (!subflow)
+		return;
+
+	ssk = subflow->tcp_sock;
+	sk = subflow->conn;
 	tp = tcp_sk(ssk);
 
 	subflow->is_mptfo = 1;
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index b30cea2fbf3fd0..355f798d575a40 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -1192,9 +1192,8 @@ bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 	 */
 	if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
 		if (mp_opt.data_fin && mp_opt.data_len == 1 &&
-		    mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64) &&
-		    schedule_work(&msk->work))
-			sock_hold(subflow->conn);
+		    mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64))
+			mptcp_schedule_work((struct sock *)msk);
 
 		return true;
 	}
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 60b23b2716c408..06c5872e3b0036 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2626,7 +2626,7 @@ static void mptcp_worker(struct work_struct *work)
 
 	lock_sock(sk);
 	state = sk->sk_state;
-	if (unlikely(state == TCP_CLOSE))
+	if (unlikely((1 << state) & (TCPF_CLOSE | TCPF_LISTEN)))
 		goto unlock;
 
 	mptcp_check_data_fin_ack(sk);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index a0041360ee9d95..d3458885054570 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -408,9 +408,8 @@ void mptcp_subflow_reset(struct sock *ssk)
 
 	tcp_send_active_reset(ssk, GFP_ATOMIC);
 	tcp_done(ssk);
-	if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) &&
-	    schedule_work(&mptcp_sk(sk)->work))
-		return; /* worker will put sk for us */
+	if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags))
+		mptcp_schedule_work(sk);
 
 	sock_put(sk);
 }
@@ -1118,8 +1117,8 @@ static enum mapping_status get_mapping_status(struct sock *ssk,
 				skb_ext_del(skb, SKB_EXT_MPTCP);
 				return MAPPING_OK;
 			} else {
-				if (updated && schedule_work(&msk->work))
-					sock_hold((struct sock *)msk);
+				if (updated)
+					mptcp_schedule_work((struct sock *)msk);
 
 				return MAPPING_DATA_FIN;
 			}
@@ -1222,17 +1221,12 @@ static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
 /* sched mptcp worker to remove the subflow if no more data is pending */
 static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
 {
-	struct sock *sk = (struct sock *)msk;
-
 	if (likely(ssk->sk_state != TCP_CLOSE))
 		return;
 
 	if (skb_queue_empty(&ssk->sk_receive_queue) &&
-	    !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) {
-		sock_hold(sk);
-		if (!schedule_work(&msk->work))
-			sock_put(sk);
-	}
+	    !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
+		mptcp_schedule_work((struct sock *)msk);
 }
 
 static bool subflow_can_fallback(struct mptcp_subflow_context *subflow)
diff --git a/tools/testing/selftests/net/mptcp/userspace_pm.sh b/tools/testing/selftests/net/mptcp/userspace_pm.sh
index 48e52f995a98c8..b1eb7bce599dc0 100755
--- a/tools/testing/selftests/net/mptcp/userspace_pm.sh
+++ b/tools/testing/selftests/net/mptcp/userspace_pm.sh
@@ -913,6 +913,7 @@ test_listener()
 		$client4_port > /dev/null 2>&1 &
 	local listener_pid=$!
 
+	sleep 0.5
 	verify_listener_events $client_evts $LISTENER_CREATED $AF_INET 10.0.2.2 $client4_port
 
 	# ADD_ADDR from client to server machine reusing the subflow port
@@ -928,6 +929,7 @@ test_listener()
 	# Delete the listener from the client ns, if one was created
 	kill_wait $listener_pid
 
+	sleep 0.5
 	verify_listener_events $client_evts $LISTENER_CLOSED $AF_INET 10.0.2.2 $client4_port
 }