This is a note to let you know that I've just added the patch titled

    mptcp: pm: fix ID 0 endp usage after multiple re-creations

to the 6.1-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-pm-fix-id-0-endp-usage-after-multiple-re-creations.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From stable+bounces-73006-greg=kroah.com@vger.kernel.org Wed Sep  4 13:04:07 2024
From: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>
Date: Wed,  4 Sep 2024 13:03:09 +0200
Subject: mptcp: pm: fix ID 0 endp usage after multiple re-creations
To: mptcp@lists.linux.dev, stable@vger.kernel.org, gregkh@linuxfoundation.org
Cc: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>, "Arınç ÜNAL" <arinc.unal@arinc9.com>, syzbot+455d38ecd5f655fc45cf@syzkaller.appspotmail.com, "Mat Martineau" <martineau@kernel.org>, "Paolo Abeni" <pabeni@redhat.com>
Message-ID: <20240904110306.4082410-6-matttbe@kernel.org>

From: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>

commit 9366922adc6a71378ca01f898c41be295309f044 upstream.

'local_addr_used' and 'add_addr_accepted' are decremented for addresses
not related to the initial subflow (ID0), because the source and
destination addresses of the initial subflows are known from the
beginning: they don't count as "additional local address being used" or
"ADD_ADDR being accepted".

It is then required not to increment them when the entrypoint used by
the initial subflow is removed and re-added during a connection. Without
this modification, this entrypoint cannot be removed and re-added more
than once.

Reported-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/512
Fixes: 3ad14f54bd74 ("mptcp: more accurate MPC endpoint tracking")
Reported-by: syzbot+455d38ecd5f655fc45cf@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/00000000000049861306209237f4@google.com
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>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/mptcp/pm_netlink.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -627,12 +627,13 @@ subflow:
 
 		fullmesh = !!(local.flags & MPTCP_PM_ADDR_FLAG_FULLMESH);
 
-		msk->pm.local_addr_used++;
 		__clear_bit(local.addr.id, msk->pm.id_avail_bitmap);
 
 		/* Special case for ID0: set the correct ID */
 		if (local.addr.id == msk->mpc_endpoint_id)
 			local.addr.id = 0;
+		else /* local_addr_used is not decr for ID 0 */
+			msk->pm.local_addr_used++;
 
 		nr = fill_remote_addresses_vec(msk, &local.addr, fullmesh, addrs);
 		if (nr == 0)
@@ -758,7 +759,9 @@ static void mptcp_pm_nl_add_addr_receive
 	spin_lock_bh(&msk->pm.lock);
 
 	if (sf_created) {
-		msk->pm.add_addr_accepted++;
+		/* add_addr_accepted is not decr for ID 0 */
+		if (remote.id)
+			msk->pm.add_addr_accepted++;
 		if (msk->pm.add_addr_accepted >= add_addr_accept_max ||
 		    msk->pm.subflows >= subflows_max)
 			WRITE_ONCE(msk->pm.accept_addr, false);


Patches currently in stable-queue which might be from matttbe@kernel.org are

queue-6.1/mptcp-pm-fix-rm_addr-id-for-the-initial-subflow.patch
queue-6.1/selftests-mptcp-join-validate-fullmesh-endp-on-1st-sf.patch
queue-6.1/mptcp-pm-fix-id-0-endp-usage-after-multiple-re-creations.patch
queue-6.1/mptcp-make-pm_remove_addrs_and_subflows-static.patch
queue-6.1/mptcp-pm-avoid-possible-uaf-when-selecting-endp.patch
queue-6.1/mptcp-pm-reuse-id-0-after-delete-and-re-add.patch
queue-6.1/selftests-mptcp-join-check-re-adding-init-endp-with-id.patch
queue-6.1/selftests-mptcp-join-test-for-flush-re-add-endpoints.patch
queue-6.1/selftests-mptcp-add-explicit-test-case-for-remove-re.patch
queue-6.1/selftests-mptcp-add-explicit-test-case-for-remove-readd.patch
queue-6.1/selftests-mptcp-join-check-re-adding-init-endp-with-.patch
queue-6.1/selftests-mptcp-join-check-re-using-id-of-closed-subflow.patch
queue-6.1/mptcp-pm-fullmesh-select-the-right-id-later.patch
queue-6.1/mptcp-pr_debug-add-missing-n-at-the-end.patch
queue-6.1/selftests-mptcp-join-check-re-using-id-of-unused-add.patch
queue-6.1/selftests-mptcp-join-check-re-using-id-of-unused-add_addr.patch