CVE-2026-64227: ACPI: driver: Check ACPI_COMPANION() against NULL during probe

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

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

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

ACPI: driver: Check ACPI_COMPANION() against NULL during probe

Since every platform driver can be forced to match a device that doesn't
match its list of device IDs because of device_match_driver_override(),
platform drivers that rely on the existence of a device's ACPI companion
object should verify its presence.

Accordingly, add requisite ACPI_COMPANION() or ACPI_HANDLE() checks
against NULL to 13 platform drivers handling core ACPI devices.

Also change the value returned by the ACPI thermal zone driver when
the device's ACPI companion is not present to -ENODEV for consistency
with the other drivers.

The Linux kernel CVE team has assigned CVE-2026-64227 to this issue.


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

	Fixed in 6.6.145 with commit f1e12d81f9cd250e722da01c7670b518d4181406
	Fixed in 6.12.97 with commit a9451bf561232314755baf69a5916e0ac77f33fc
	Fixed in 6.18.40 with commit 34f4d0e4e5065237d15651df759a99e81b7f9f51
	Fixed in 7.0.11 with commit 612ddab8fce04394bd7aebe8e0f2599642e30859
	Fixed in 7.1 with commit e4865a56d013e86e46ea6acea15bb6eae01898ff

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-2026-64227
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/acpi/ac.c
	drivers/acpi/acpi_pad.c
	drivers/acpi/acpi_tad.c
	drivers/acpi/battery.c
	drivers/acpi/button.c
	drivers/acpi/ec.c
	drivers/acpi/hed.c
	drivers/acpi/nfit/core.c
	drivers/acpi/pfr_telemetry.c
	drivers/acpi/pfr_update.c
	drivers/acpi/sbs.c
	drivers/acpi/sbshc.c
	drivers/acpi/thermal.c
	drivers/acpi/tiny-power-button.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/f1e12d81f9cd250e722da01c7670b518d4181406
	https://git.kernel.org/stable/c/a9451bf561232314755baf69a5916e0ac77f33fc
	https://git.kernel.org/stable/c/34f4d0e4e5065237d15651df759a99e81b7f9f51
	https://git.kernel.org/stable/c/612ddab8fce04394bd7aebe8e0f2599642e30859
	https://git.kernel.org/stable/c/e4865a56d013e86e46ea6acea15bb6eae01898ff