CVE-2024-45010: mptcp: pm: only mark 'subflow' endp as available

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

mptcp: pm: only mark 'subflow' endp as available

Adding the following warning ...

  WARN_ON_ONCE(msk->pm.local_addr_used == 0)

... before decrementing the local_addr_used counter helped to find a bug
when running the "remove single address" subtest from the mptcp_join.sh
selftests.

Removing a 'signal' endpoint will trigger the removal of all subflows
linked to this endpoint via mptcp_pm_nl_rm_addr_or_subflow() with
rm_type == MPTCP_MIB_RMSUBFLOW. This will decrement the local_addr_used
counter, which is wrong in this case because this counter is linked to
'subflow' endpoints, and here it is a 'signal' endpoint that is being
removed.

Now, the counter is decremented, only if the ID is being used outside
of mptcp_pm_nl_rm_addr_or_subflow(), only for 'subflow' endpoints, and
if the ID is not 0 -- local_addr_used is not taking into account these
ones. This marking of the ID as being available, and the decrement is
done no matter if a subflow using this ID is currently available,
because the subflow could have been closed before.

The Linux kernel CVE team has assigned CVE-2024-45010 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.13 with commit 06faa2271034 and fixed in 6.1.108 with commit 7fdc870d0896
	Issue introduced in 5.13 with commit 06faa2271034 and fixed in 6.6.48 with commit 43cf912b0b0f
	Issue introduced in 5.13 with commit 06faa2271034 and fixed in 6.10.7 with commit 9849cfc67383
	Issue introduced in 5.13 with commit 06faa2271034 and fixed in 6.11-rc5 with commit 322ea3778965

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-45010
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/mptcp/pm_netlink.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/7fdc870d08960961408a44c569f20f50940e7d4f
	https://git.kernel.org/stable/c/43cf912b0b0fc7b4fd12cbc735d1f5afb8e1322d
	https://git.kernel.org/stable/c/9849cfc67383ceb167155186f8f8fe8a896b60b3
	https://git.kernel.org/stable/c/322ea3778965da72862cca2a0c50253aacf65fe6