CVE-2026-98705: wifi: mac80211: account proxy paths against the mesh path limit

CVE-2026-98705: wifi: mac80211: account proxy paths against the mesh path limit

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

wifi: mac80211: account proxy paths against the mesh path limit

Proxy-path churn can drive the interface path counter negative and let
later mesh path additions exceed MESH_MAX_MPATHS.

mesh_path_free_rcu() decrements the interface mpaths counter for entries
from both the mesh and proxy path tables, but mpp_path_add() never
reserves a slot in that counter. Removing or expiring a proxy path
therefore returns a slot that was never charged.

mesh_path_add() uses the same counter to enforce MESH_MAX_MPATHS, so once
it falls below the number of installed paths the limit no longer holds.

Reserve the shared quota before allocating a proxy path and release it on
every unsuccessful addition. Mesh and proxy paths now share one
1024-entry budget, so mpp_path_add() can return -ENOSPC at that limit.

The Linux kernel CVE team has assigned CVE-2026-98705 to this issue.


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

	Issue introduced in 3.2 with commit ece1a2e7e86078c8379937b546e32cb7f25fcb6c and fixed in 6.12.113 with commit df072db65fdaa34ad15e1d66fc06a53e3e97f778
	Issue introduced in 3.2 with commit ece1a2e7e86078c8379937b546e32cb7f25fcb6c and fixed in 6.18.56 with commit 3b75831ceee76d32bb8e7ddd241904f92f9b5407
	Issue introduced in 3.2 with commit ece1a2e7e86078c8379937b546e32cb7f25fcb6c and fixed in 7.2.10 with commit 5a32409ed34a1868830899a5d2437f0b3bf3532c
	Issue introduced in 3.2 with commit ece1a2e7e86078c8379937b546e32cb7f25fcb6c and fixed in 7.3-rc6 with commit a5f35d4b112af1415ff06bd501c8cc26cc08aa8b

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-2026-98705
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/mac80211/mesh_pathtbl.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/df072db65fdaa34ad15e1d66fc06a53e3e97f778
	https://git.kernel.org/stable/c/3b75831ceee76d32bb8e7ddd241904f92f9b5407
	https://git.kernel.org/stable/c/5a32409ed34a1868830899a5d2437f0b3bf3532c
	https://git.kernel.org/stable/c/a5f35d4b112af1415ff06bd501c8cc26cc08aa8b