CVE-2026-68408: wifi: cfg80211: convert pmsr_free_wk to wiphy_work to fix deadlock

From: Greg Kroah-Hartman <[email protected]>

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

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

wifi: cfg80211: convert pmsr_free_wk to wiphy_work to fix deadlock

When a netlink socket that owns a PMSR session is closed,
cfg80211_release_pmsr() clears the request's nl_portid and queues
pmsr_free_wk to call cfg80211_pmsr_process_abort() asynchronously.

If the interface tears down concurrently, cfg80211_pmsr_wdev_down()
is called under wiphy_lock and calls cancel_work_sync(&pmsr_free_wk)
to wait for any running work. The work function acquires wiphy_lock
via guard(wiphy) before calling process_abort.

This is a deadlock: wdev_down holds wiphy_lock and blocks inside
cancel_work_sync(); pmsr_free_wk blocks trying to acquire that same
wiphy_lock. Neither thread can proceed.

The same deadlock is reachable from cfg80211_leave_locked(), which
calls cfg80211_pmsr_wdev_down() for all interface types under
wiphy_lock.

Fix this by converting pmsr_free_wk from a plain work_struct to a
wiphy_work. The wiphy_work dispatcher holds wiphy_lock when running
work items, so the explicit guard(wiphy) in the work function is no
longer needed. wiphy_work_cancel() can be called safely while holding
wiphy_lock - since wiphy_lock prevents the work from running
concurrently, wiphy_work_cancel() never blocks, eliminating the
deadlock.

Remove the cancel_work_sync() for pmsr_free_wk from the
NETDEV_GOING_DOWN handler. cfg80211_leave(), called unconditionally
just before it, already cancels any pending work under wiphy_lock
via wiphy_work_cancel() inside cfg80211_pmsr_wdev_down().

The Linux kernel CVE team has assigned CVE-2026-68408 to this issue.


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

	Issue introduced in 6.12.78 with commit d32c07ef1880fe20cf4ab223dbfedc9c0b2816aa and fixed in 6.12.101 with commit 21512b5f7a74fd18c996c22e6854efe57d570816
	Issue introduced in 6.18.20 with commit a1b7a843f12a0c3e9d3a2ca607ce451916ef42cf and fixed in 6.18.42 with commit 133684982dd0c24359fcc641d19d89cc17d6e5ef
	Issue introduced in 7.0 with commit 6dccbc9f3e1d38565dff7730d2b7d1e8b16c9b09 and fixed in 7.1.6 with commit 0a77d9fb4d5c0e01306cd406ffdee8f1fe955c0e
	Issue introduced in 7.0 with commit 6dccbc9f3e1d38565dff7730d2b7d1e8b16c9b09 and fixed in 7.2-rc4 with commit 2b0eab425e1f658d8fe1df7590e3b9af5959505e
	Issue introduced in 6.1.167 with commit 28d3551f8d8cb3aec7497894d94150fe84d20e5e
	Issue introduced in 6.6.130 with commit 37e776e2e0a523731e2470dce6d563f0e8632a40
	Issue introduced in 6.19.10 with commit 72b7ea786b8e570ae11149e9089859a4a8634a13

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-2026-68408
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:
	include/net/cfg80211.h
	net/wireless/core.c
	net/wireless/core.h
	net/wireless/pmsr.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/21512b5f7a74fd18c996c22e6854efe57d570816
	https://git.kernel.org/stable/c/133684982dd0c24359fcc641d19d89cc17d6e5ef
	https://git.kernel.org/stable/c/0a77d9fb4d5c0e01306cd406ffdee8f1fe955c0e
	https://git.kernel.org/stable/c/2b0eab425e1f658d8fe1df7590e3b9af5959505e