[PATCH 6.1 0/2] mptcp: Stable backports for v6.1.26

[PATCH 6.1 0/2] mptcp: Stable backports for v6.1.26

[Matthieu Baerts]

Hi Greg, Sasha,

Recently, 2 patches related to MPTCP have not been backported to v6.1
tree due to conflicts:

 - 2a6a870e44dd ("mptcp: stops worker on unaccepted sockets at listener close") [1]
 - 63740448a32e ("mptcp: fix accept vs worker race") [2]

I then here resolved the conflicts, documented what I did in each patch
and ran our tests suite. Everything seems OK.

These patches are based on top of the latest linux-stable-rc/linux-6.1.y
version.

Do you mind adding these two patches to v6.1 queue please?

[1] https://lore.kernel.org/r/2023042259-gravity-hate-a9a3@gregkh
[2] https://lore.kernel.org/r/2023042215-chastise-scuba-8478@gregkh

Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
---
Paolo Abeni (2):
      mptcp: stops worker on unaccepted sockets at listener close
      mptcp: fix accept vs worker race

 net/mptcp/protocol.c | 74 +++++++++++++++++++++++++++++++++---------------
 net/mptcp/protocol.h |  2 ++
 net/mptcp/subflow.c  | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 130 insertions(+), 26 deletions(-)
---
base-commit: e4ff6ff54dea67f94036a357201b0f9807405cc6
change-id: 20230424-upstream-stable-20230424-conflicts-6-1-f325fe76c540

Best regards,
-- 
Matthieu Baerts <matthieu.baerts@tessares.net>

[PATCH 6.1 1/2] mptcp: stops worker on unaccepted sockets at listener close

[Matthieu Baerts]

From: Paolo Abeni <pabeni@redhat.com>

[ Upstream commit 2a6a870e44dd88f1a6a2893c65ef756a9edfb4c7 ]

  Backports notes: similar to the conflicts with the partially reverted
  commit 5564be74a22a ("mptcp: fix UaF in listener shutdown"), there was
  one simple conflict in net/mptcp/protocol.c with:

    commit f8c9dfbd875b ("mptcp: add pm listener events")

  We just need to omit one line linked to the PM listener event.

This is a partial revert of the blamed commit, with a relevant
change: mptcp_subflow_queue_clean() now just change the msk
socket status and stop the worker, so that the UaF issue addressed
by the blamed commit is not re-introduced.

The above prevents the mptcp worker from running concurrently with
inet_csk_listen_stop(), as such race would trigger a warning, as
reported by Christoph:

RSP: 002b:00007f784fe09cd8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
WARNING: CPU: 0 PID: 25807 at net/ipv4/inet_connection_sock.c:1387 inet_csk_listen_stop+0x664/0x870 net/ipv4/inet_connection_sock.c:1387
RAX: ffffffffffffffda RBX: 00000000006bc050 RCX: 00007f7850afd6a9
RDX: 0000000000000000 RSI: 0000000020000340 RDI: 0000000000000004
Modules linked in:
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006bc05c
R13: fffffffffffffea8 R14: 00000000006bc050 R15: 000000000001fe40

 </TASK>
CPU: 0 PID: 25807 Comm: syz-executor.7 Not tainted 6.2.0-g778e54711659 #7
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014
RIP: 0010:inet_csk_listen_stop+0x664/0x870 net/ipv4/inet_connection_sock.c:1387
RAX: 0000000000000000 RBX: ffff888100dfbd40 RCX: 0000000000000000
RDX: ffff8881363aab80 RSI: ffffffff81c494f4 RDI: 0000000000000005
RBP: ffff888126dad080 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888100dfe040
R13: 0000000000000001 R14: 0000000000000000 R15: ffff888100dfbdd8
FS:  00007f7850a2c800(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32d26000 CR3: 000000012fdd8006 CR4: 0000000000770ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 <TASK>
 __tcp_close+0x5b2/0x620 net/ipv4/tcp.c:2875
 __mptcp_close_ssk+0x145/0x3d0 net/mptcp/protocol.c:2427
 mptcp_destroy_common+0x8a/0x1c0 net/mptcp/protocol.c:3277
 mptcp_destroy+0x41/0x60 net/mptcp/protocol.c:3304
 __mptcp_destroy_sock+0x56/0x140 net/mptcp/protocol.c:2965
 __mptcp_close+0x38f/0x4a0 net/mptcp/protocol.c:3057
 mptcp_close+0x24/0xe0 net/mptcp/protocol.c:3072
 inet_release+0x53/0xa0 net/ipv4/af_inet.c:429
 __sock_release+0x4e/0xf0 net/socket.c:651
 sock_close+0x15/0x20 net/socket.c:1393
 __fput+0xff/0x420 fs/file_table.c:321
 task_work_run+0x8b/0xe0 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x113/0x120 kernel/entry/common.c:203
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:296
 do_syscall_64+0x46/0x90 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x7f7850af70dc
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007f7850af70dc
RDX: 00007f7850a2c800 RSI: 0000000000000002 RDI: 0000000000000003
RBP: 00000000006bd980 R08: 0000000000000000 R09: 00000000000018a0
R10: 00000000316338a4 R11: 0000000000000293 R12: 0000000000211e31
R13: 00000000006bc05c R14: 00007f785062c000 R15: 0000000000211af0

Fixes: 0a3f4f1f9c27 ("mptcp: fix UaF in listener shutdown")
Cc: stable@vger.kernel.org
Reported-by: Christoph Paasch <cpaasch@apple.com>
Link: https://github.com/multipath-tcp/mptcp_net-next/issues/371
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>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
---
 net/mptcp/protocol.c |  6 +++++
 net/mptcp/protocol.h |  1 +
 net/mptcp/subflow.c  | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 79 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index b1bbb0b75a13..a4d5072c6e98 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2380,6 +2380,12 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 		mptcp_subflow_drop_ctx(ssk);
 	} 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);
+		}
+
 		__tcp_close(ssk, 0);
 
 		/* close acquired an extra ref */
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 051e8022d661..2cddd5b52e8f 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -615,6 +615,7 @@ void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 		     struct mptcp_subflow_context *subflow);
 void __mptcp_subflow_send_ack(struct sock *ssk);
 void mptcp_subflow_reset(struct sock *ssk);
+void mptcp_subflow_queue_clean(struct sock *sk, struct sock *ssk);
 void mptcp_sock_graft(struct sock *sk, struct socket *parent);
 struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk);
 bool __mptcp_close(struct sock *sk, long timeout);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 125d1f58d6a4..d9bc4bdb94b7 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1758,6 +1758,78 @@ static void subflow_state_change(struct sock *sk)
 	}
 }
 
+void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
+{
+	struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
+	struct mptcp_sock *msk, *next, *head = NULL;
+	struct request_sock *req;
+
+	/* build a list of all unaccepted mptcp sockets */
+	spin_lock_bh(&queue->rskq_lock);
+	for (req = queue->rskq_accept_head; req; req = req->dl_next) {
+		struct mptcp_subflow_context *subflow;
+		struct sock *ssk = req->sk;
+
+		if (!sk_is_mptcp(ssk))
+			continue;
+
+		subflow = mptcp_subflow_ctx(ssk);
+		if (!subflow || !subflow->conn)
+			continue;
+
+		/* skip if already in list */
+		msk = mptcp_sk(subflow->conn);
+		if (msk->dl_next || msk == head)
+			continue;
+
+		sock_hold(subflow->conn);
+		msk->dl_next = head;
+		head = msk;
+	}
+	spin_unlock_bh(&queue->rskq_lock);
+	if (!head)
+		return;
+
+	/* can't acquire the msk socket lock under the subflow one,
+	 * or will cause ABBA deadlock
+	 */
+	release_sock(listener_ssk);
+
+	for (msk = head; msk; msk = next) {
+		struct sock *sk = (struct sock *)msk;
+
+		lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
+		next = msk->dl_next;
+		msk->dl_next = NULL;
+
+		/* prevent the stack from later re-schedule the worker for
+		 * this socket
+		 */
+		inet_sk_state_store(sk, TCP_CLOSE);
+		release_sock(sk);
+
+		/* lockdep will report a false positive ABBA deadlock
+		 * between cancel_work_sync and the listener socket.
+		 * The involved locks belong to different sockets WRT
+		 * the existing AB chain.
+		 * Using a per socket key is problematic as key
+		 * deregistration requires process context and must be
+		 * performed at socket disposal time, in atomic
+		 * context.
+		 * Just tell lockdep to consider the listener socket
+		 * released here.
+		 */
+		mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
+		mptcp_cancel_work(sk);
+		mutex_acquire(&listener_sk->sk_lock.dep_map, 0, 0, _RET_IP_);
+
+		sock_put(sk);
+	}
+
+	/* we are still under the listener msk socket lock */
+	lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING);
+}
+
 static int subflow_ulp_init(struct sock *sk)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);

-- 
2.39.2

[PATCH 6.1 2/2] mptcp: fix accept vs worker race

[Matthieu Baerts]

From: Paolo Abeni <pabeni@redhat.com>

[ Upstream commit 63740448a32eb662e05894425b47bcc5814136f4 ]

  Backports notes: one simple conflict in net/mptcp/protocol.h with

    commit 36b122baf6a8 ("mptcp: add subflow_v(4,6)_send_synack()")

  Where the two commits add the signature of one function in protocol.h
  at the same place.

The mptcp worker and mptcp_accept() can race, as reported by Christoph:

refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 14351 at lib/refcount.c:25 refcount_warn_saturate+0x105/0x1b0 lib/refcount.c:25
Modules linked in:
CPU: 1 PID: 14351 Comm: syz-executor.2 Not tainted 6.3.0-rc1-gde5e8fd0123c #11
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014
RIP: 0010:refcount_warn_saturate+0x105/0x1b0 lib/refcount.c:25
Code: 02 31 ff 89 de e8 1b f0 a7 ff 84 db 0f 85 6e ff ff ff e8 3e f5 a7 ff 48 c7 c7 d8 c7 34 83 c6 05 6d 2d 0f 02 01 e8 cb 3d 90 ff <0f> 0b e9 4f ff ff ff e8 1f f5 a7 ff 0f b6 1d 54 2d 0f 02 31 ff 89
RSP: 0018:ffffc90000a47bf8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88802eae98c0 RSI: ffffffff81097d4f RDI: 0000000000000001
RBP: ffff88802e712180 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffff88802eaea148 R12: ffff88802e712100
R13: ffff88802e712a88 R14: ffff888005cb93a8 R15: ffff88802e712a88
FS:  0000000000000000(0000) GS:ffff88803ed00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f277fd89120 CR3: 0000000035486002 CR4: 0000000000370ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __refcount_add include/linux/refcount.h:199 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 sock_hold include/net/sock.h:775 [inline]
 __mptcp_close+0x4c6/0x4d0 net/mptcp/protocol.c:3051
 mptcp_close+0x24/0xe0 net/mptcp/protocol.c:3072
 inet_release+0x56/0xa0 net/ipv4/af_inet.c:429
 __sock_release+0x51/0xf0 net/socket.c:653
 sock_close+0x18/0x20 net/socket.c:1395
 __fput+0x113/0x430 fs/file_table.c:321
 task_work_run+0x96/0x100 kernel/task_work.c:179
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0x4fc/0x10c0 kernel/exit.c:869
 do_group_exit+0x51/0xf0 kernel/exit.c:1019
 get_signal+0x12b0/0x1390 kernel/signal.c:2859
 arch_do_signal_or_restart+0x25/0x260 arch/x86/kernel/signal.c:306
 exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
 exit_to_user_mode_prepare+0x131/0x1a0 kernel/entry/common.c:203
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x19/0x40 kernel/entry/common.c:296
 do_syscall_64+0x46/0x90 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x7fec4b4926a9
Code: Unable to access opcode bytes at 0x7fec4b49267f.
RSP: 002b:00007fec49f9dd78 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00000000006bc058 RCX: 00007fec4b4926a9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006bc058
RBP: 00000000006bc050 R08: 00000000007df998 R09: 00000000007df998
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006bc05c
R13: fffffffffffffea8 R14: 000000000000000b R15: 000000000001fe40
 </TASK>

The root cause is that the worker can force fallback to TCP the first
mptcp subflow, actually deleting the unaccepted msk socket.

We can explicitly prevent the race delaying the unaccepted msk deletion
at listener shutdown time. In case the closed subflow is later accepted,
just drop the mptcp context and let the user-space deal with the
paired mptcp socket.

Fixes: b6985b9b8295 ("mptcp: use the workqueue to destroy unaccepted sockets")
Cc: stable@vger.kernel.org
Reported-by: Christoph Paasch <cpaasch@apple.com>
Link: https://github.com/multipath-tcp/mptcp_net-next/issues/375
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Tested-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
---
 net/mptcp/protocol.c | 68 ++++++++++++++++++++++++++++++++++------------------
 net/mptcp/protocol.h |  1 +
 net/mptcp/subflow.c  | 22 +++++++++--------
 3 files changed, 58 insertions(+), 33 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index a4d5072c6e98..ea46a5cb1c30 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2330,7 +2330,26 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 			      unsigned int flags)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
-	bool need_push, dispose_it;
+	bool dispose_it, need_push = false;
+
+	/* If the first subflow moved to a close state before accept, e.g. due
+	 * to an incoming reset, mptcp either:
+	 * - if either the subflow or the msk are dead, destroy the context
+	 *   (the subflow socket is deleted by inet_child_forget) and the msk
+	 * - otherwise do nothing at the moment and take action at accept and/or
+	 *   listener shutdown - user-space must be able to accept() the closed
+	 *   socket.
+	 */
+	if (msk->in_accept_queue && msk->first == ssk) {
+		if (!sock_flag(sk, SOCK_DEAD) && !sock_flag(ssk, SOCK_DEAD))
+			return;
+
+		/* ensure later check in mptcp_worker() will dispose the msk */
+		sock_set_flag(sk, SOCK_DEAD);
+		lock_sock_nested(ssk, SINGLE_DEPTH_NESTING);
+		mptcp_subflow_drop_ctx(ssk);
+		goto out_release;
+	}
 
 	dispose_it = !msk->subflow || ssk != msk->subflow->sk;
 	if (dispose_it)
@@ -2366,18 +2385,6 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 	if (!inet_csk(ssk)->icsk_ulp_ops) {
 		WARN_ON_ONCE(!sock_flag(ssk, SOCK_DEAD));
 		kfree_rcu(subflow, rcu);
-	} else if (msk->in_accept_queue && msk->first == ssk) {
-		/* if the first subflow moved to a close state, e.g. due to
-		 * incoming reset and we reach here before inet_child_forget()
-		 * the TCP stack could later try to close it via
-		 * inet_csk_listen_stop(), or deliver it to the user space via
-		 * accept().
-		 * We can't delete the subflow - or risk a double free - nor let
-		 * the msk survive - or will be leaked in the non accept scenario:
-		 * fallback and let TCP cope with the subflow cleanup.
-		 */
-		WARN_ON_ONCE(sock_flag(ssk, SOCK_DEAD));
-		mptcp_subflow_drop_ctx(ssk);
 	} else {
 		/* otherwise tcp will dispose of the ssk and subflow ctx */
 		if (ssk->sk_state == TCP_LISTEN) {
@@ -2391,6 +2398,8 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 		/* close acquired an extra ref */
 		__sock_put(ssk);
 	}
+
+out_release:
 	release_sock(ssk);
 
 	sock_put(ssk);
@@ -2445,21 +2454,14 @@ static void __mptcp_close_subflow(struct sock *sk)
 		mptcp_close_ssk(sk, ssk, subflow);
 	}
 
-	/* if the MPC subflow has been closed before the msk is accepted,
-	 * msk will never be accept-ed, close it now
-	 */
-	if (!msk->first && msk->in_accept_queue) {
-		sock_set_flag(sk, SOCK_DEAD);
-		inet_sk_state_store(sk, TCP_CLOSE);
-	}
 }
 
-static bool mptcp_check_close_timeout(const struct sock *sk)
+static bool mptcp_should_close(const struct sock *sk)
 {
 	s32 delta = tcp_jiffies32 - inet_csk(sk)->icsk_mtup.probe_timestamp;
 	struct mptcp_subflow_context *subflow;
 
-	if (delta >= TCP_TIMEWAIT_LEN)
+	if (delta >= TCP_TIMEWAIT_LEN || mptcp_sk(sk)->in_accept_queue)
 		return true;
 
 	/* if all subflows are in closed status don't bother with additional
@@ -2667,7 +2669,7 @@ static void mptcp_worker(struct work_struct *work)
 	 * even if it is orphaned and in FIN_WAIT2 state
 	 */
 	if (sock_flag(sk, SOCK_DEAD)) {
-		if (mptcp_check_close_timeout(sk)) {
+		if (mptcp_should_close(sk)) {
 			inet_sk_state_store(sk, TCP_CLOSE);
 			mptcp_do_fastclose(sk);
 		}
@@ -2912,6 +2914,14 @@ static void __mptcp_destroy_sock(struct sock *sk)
 	sock_put(sk);
 }
 
+void __mptcp_unaccepted_force_close(struct sock *sk)
+{
+	sock_set_flag(sk, SOCK_DEAD);
+	inet_sk_state_store(sk, TCP_CLOSE);
+	mptcp_do_fastclose(sk);
+	__mptcp_destroy_sock(sk);
+}
+
 static __poll_t mptcp_check_readable(struct mptcp_sock *msk)
 {
 	/* Concurrent splices from sk_receive_queue into receive_queue will
@@ -3759,6 +3769,18 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
 			if (!ssk->sk_socket)
 				mptcp_sock_graft(ssk, newsock);
 		}
+
+		/* Do late cleanup for the first subflow as necessary. Also
+		 * deal with bad peers not doing a complete shutdown.
+		 */
+		if (msk->first &&
+		    unlikely(inet_sk_state_load(msk->first) == TCP_CLOSE)) {
+			__mptcp_close_ssk(newsk, msk->first,
+					  mptcp_subflow_ctx(msk->first), 0);
+			if (unlikely(list_empty(&msk->conn_list)))
+				inet_sk_state_store(newsk, TCP_CLOSE);
+		}
+
 		release_sock(newsk);
 	}
 
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 2cddd5b52e8f..441feeaeb242 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -620,6 +620,7 @@ void mptcp_sock_graft(struct sock *sk, struct socket *parent);
 struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk);
 bool __mptcp_close(struct sock *sk, long timeout);
 void mptcp_cancel_work(struct sock *sk);
+void __mptcp_unaccepted_force_close(struct sock *sk);
 
 bool mptcp_addresses_equal(const struct mptcp_addr_info *a,
 			   const struct mptcp_addr_info *b, bool use_port);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index d9bc4bdb94b7..67ddbf6f2e4e 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -661,9 +661,12 @@ void mptcp_subflow_drop_ctx(struct sock *ssk)
 	if (!ctx)
 		return;
 
-	subflow_ulp_fallback(ssk, ctx);
-	if (ctx->conn)
-		sock_put(ctx->conn);
+	list_del(&mptcp_subflow_ctx(ssk)->node);
+	if (inet_csk(ssk)->icsk_ulp_ops) {
+		subflow_ulp_fallback(ssk, ctx);
+		if (ctx->conn)
+			sock_put(ctx->conn);
+	}
 
 	kfree_rcu(ctx, rcu);
 }
@@ -1763,6 +1766,7 @@ void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_s
 	struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
 	struct mptcp_sock *msk, *next, *head = NULL;
 	struct request_sock *req;
+	struct sock *sk;
 
 	/* build a list of all unaccepted mptcp sockets */
 	spin_lock_bh(&queue->rskq_lock);
@@ -1778,11 +1782,12 @@ void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_s
 			continue;
 
 		/* skip if already in list */
-		msk = mptcp_sk(subflow->conn);
+		sk = subflow->conn;
+		msk = mptcp_sk(sk);
 		if (msk->dl_next || msk == head)
 			continue;
 
-		sock_hold(subflow->conn);
+		sock_hold(sk);
 		msk->dl_next = head;
 		head = msk;
 	}
@@ -1796,16 +1801,13 @@ void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_s
 	release_sock(listener_ssk);
 
 	for (msk = head; msk; msk = next) {
-		struct sock *sk = (struct sock *)msk;
+		sk = (struct sock *)msk;
 
 		lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
 		next = msk->dl_next;
 		msk->dl_next = NULL;
 
-		/* prevent the stack from later re-schedule the worker for
-		 * this socket
-		 */
-		inet_sk_state_store(sk, TCP_CLOSE);
+		__mptcp_unaccepted_force_close(sk);
 		release_sock(sk);
 
 		/* lockdep will report a false positive ABBA deadlock

-- 
2.39.2

Re: [PATCH 6.1 0/2] mptcp: Stable backports for v6.1.26

[Greg Kroah-Hartman]

On Mon, Apr 24, 2023 at 04:09:07PM +0200, Matthieu Baerts wrote:
> Hi Greg, Sasha,
> 
> Recently, 2 patches related to MPTCP have not been backported to v6.1
> tree due to conflicts:
> 
>  - 2a6a870e44dd ("mptcp: stops worker on unaccepted sockets at listener close") [1]
>  - 63740448a32e ("mptcp: fix accept vs worker race") [2]
> 
> I then here resolved the conflicts, documented what I did in each patch
> and ran our tests suite. Everything seems OK.
> 
> These patches are based on top of the latest linux-stable-rc/linux-6.1.y
> version.
> 
> Do you mind adding these two patches to v6.1 queue please?
> 
> [1] https://lore.kernel.org/r/2023042259-gravity-hate-a9a3@gregkh
> [2] https://lore.kernel.org/r/2023042215-chastise-scuba-8478@gregkh
> 
> Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
> ---
> Paolo Abeni (2):
>       mptcp: stops worker on unaccepted sockets at listener close
>       mptcp: fix accept vs worker race
> 
>  net/mptcp/protocol.c | 74 +++++++++++++++++++++++++++++++++---------------
>  net/mptcp/protocol.h |  2 ++
>  net/mptcp/subflow.c  | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++--
>  3 files changed, 130 insertions(+), 26 deletions(-)
> ---
> base-commit: e4ff6ff54dea67f94036a357201b0f9807405cc6
> change-id: 20230424-upstream-stable-20230424-conflicts-6-1-f325fe76c540
> 
> Best regards,
> -- 
> Matthieu Baerts <matthieu.baerts@tessares.net>

Both now queued up, thanks.

greg k-h