CVE-2026-46308: pmdomain: mediatek: fix use-after-free in scpsys_get_bus_protection_legacy()

CVE-2026-46308: pmdomain: mediatek: fix use-after-free in scpsys_get_bus_protection_legacy()

[Greg Kroah-Hartman]

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

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

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

pmdomain: mediatek: fix use-after-free in scpsys_get_bus_protection_legacy()

In scpsys_get_bus_protection_legacy(), of_find_node_with_property()
returns a device node with its reference count incremented. The function
then calls of_node_put(node) before checking whether
syscon_regmap_lookup_by_phandle() returns an error. If an error occurs,
dev_err_probe() dereferences the node pointer to print diagnostic
information, but the node memory may have already been freed due to the
earlier of_node_put(), leading to a use-after-free vulnerability.

Fix this by moving the of_node_put() call after the error check, ensuring
the node is still valid when accessed in the error path.

The Linux kernel CVE team has assigned CVE-2026-46308 to this issue.


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

	Issue introduced in 6.18 with commit c29345fa5f66bea0790cf2219f57b974d4fc177b and fixed in 6.18.30 with commit cb27e43c0511e9e1ca8818d231656070b11c18cf
	Issue introduced in 6.18 with commit c29345fa5f66bea0790cf2219f57b974d4fc177b and fixed in 7.0.7 with commit 38d8410021b55d226847b2ac8d189d89fe5a8866
	Issue introduced in 6.18 with commit c29345fa5f66bea0790cf2219f57b974d4fc177b and fixed in 7.1-rc3 with commit ec1fcddb3117d9452210e838fd37389ee61e10e8

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-2026-46308
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/pmdomain/mediatek/mtk-pm-domains.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/cb27e43c0511e9e1ca8818d231656070b11c18cf
	https://git.kernel.org/stable/c/38d8410021b55d226847b2ac8d189d89fe5a8866
	https://git.kernel.org/stable/c/ec1fcddb3117d9452210e838fd37389ee61e10e8