CVE-2026-97599: ieee802154: hwsim: serialize pib updates to fix double-free

CVE-2026-97599: ieee802154: hwsim: serialize pib updates to fix double-free

[Greg Kroah-Hartman]

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

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

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

ieee802154: hwsim: serialize pib updates to fix double-free

hwsim_update_pib() does an unserialized read-swap-free of phy->pib:

	pib_old = rtnl_dereference(phy->pib);
	...
	rcu_assign_pointer(phy->pib, pib);
	kfree_rcu(pib_old, rcu);

It assumes the RTNL is held, but ->set_channel is not always called
under it: the mac802154 scan worker changes channels via
drv_set_channel() without the RTNL. Such an update can race an
RTNL-held one on the same phy; both read the same pib_old and both
kfree_rcu() it, double-freeing the object. With SLUB percpu sheaves
batching kfree_rcu(), this surfaces as a KASAN invalid-free in
rcu_free_sheaf().

struct hwsim_phy has no lock for pib. Add one and make the swap atomic
with rcu_replace_pointer() under it, dropping the misleading
rtnl_dereference().

The Linux kernel CVE team has assigned CVE-2026-97599 to this issue.


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

	Issue introduced in 4.19 with commit f25da51fdc381ca2863248c7060b3662632f0872 and fixed in 6.12.111 with commit 9973b3a67a7592a780ea12b08334539a900deec1
	Issue introduced in 4.19 with commit f25da51fdc381ca2863248c7060b3662632f0872 and fixed in 6.18.53 with commit d3b8f264ce09573aededd0a97dc41c8147797d8f
	Issue introduced in 4.19 with commit f25da51fdc381ca2863248c7060b3662632f0872 and fixed in 7.2.7 with commit db6442deecb1f13aeaf4f9d77746ea7555630fb3
	Issue introduced in 4.19 with commit f25da51fdc381ca2863248c7060b3662632f0872 and fixed in 7.3-rc3 with commit 979d5b8de8ed4e1f997aef12da5694b99be7b871

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-2026-97599
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:
	drivers/net/ieee802154/mac802154_hwsim.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/9973b3a67a7592a780ea12b08334539a900deec1
	https://git.kernel.org/stable/c/d3b8f264ce09573aededd0a97dc41c8147797d8f
	https://git.kernel.org/stable/c/db6442deecb1f13aeaf4f9d77746ea7555630fb3
	https://git.kernel.org/stable/c/979d5b8de8ed4e1f997aef12da5694b99be7b871