CVE-2026-74661: mac802154: fix netdev use-after-free in beacon worker

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

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

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

mac802154: fix netdev use-after-free in beacon worker

mac802154_beacon_worker() reads local->beacon_req under RCU and derives
the sub-interface from the request, but then drops the RCU read lock and
continues to use both sdata and the embedded wpan_dev.

mac802154_stop_beacons_locked() cancels only pending beacon work, clears
local->beacon_req and frees the request.  A beacon worker that is already
running can therefore continue after interface teardown and dereference
the freed netdev private area.

The scan worker already pins the netdev before leaving RCU.  Apply the
same lifetime rule to the beacon worker: take a netdev reference while
the request is still protected by RCU, and release it on all paths that
continue after the reference is acquired.

The Linux kernel CVE team has assigned CVE-2026-74661 to this issue.


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

	Issue introduced in 6.3 with commit 3accf4762734a69ebd03cba989249c78ac7dfc7e and fixed in 6.6.152 with commit fe820dcc1d8ff77783a9d2bcc93b98c99ac6d517
	Issue introduced in 6.3 with commit 3accf4762734a69ebd03cba989249c78ac7dfc7e and fixed in 6.12.104 with commit e5fb0e03bc7f45508c182a427357bf6b389a9033
	Issue introduced in 6.3 with commit 3accf4762734a69ebd03cba989249c78ac7dfc7e and fixed in 6.18.45 with commit e6cd416a899edc912b428c4ba399bd73f516cb31
	Issue introduced in 6.3 with commit 3accf4762734a69ebd03cba989249c78ac7dfc7e and fixed in 7.1.9 with commit 9d067e581597c462c51fee8a30b51bc48a68c4e1
	Issue introduced in 6.3 with commit 3accf4762734a69ebd03cba989249c78ac7dfc7e and fixed in 7.2 with commit 5f26a690e8efa54315e4922368daf54e0b8f5515

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-2026-74661
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/mac802154/scan.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/fe820dcc1d8ff77783a9d2bcc93b98c99ac6d517
	https://git.kernel.org/stable/c/e5fb0e03bc7f45508c182a427357bf6b389a9033
	https://git.kernel.org/stable/c/e6cd416a899edc912b428c4ba399bd73f516cb31
	https://git.kernel.org/stable/c/9d067e581597c462c51fee8a30b51bc48a68c4e1
	https://git.kernel.org/stable/c/5f26a690e8efa54315e4922368daf54e0b8f5515