CVE-2026-68238: drm/amdgpu: Release VFCT ACPI table reference

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

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

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

drm/amdgpu: Release VFCT ACPI table reference

amdgpu_acpi_vfct_bios() fetches the VFCT table with acpi_get_table()
but never releases it. acpi_get_table() takes a reference on the
table (incrementing its validation_count and mapping it on the 0->1
transition); without a paired acpi_put_table() the mapping is leaked
on every call, whether or not a matching VBIOS image is found.

Route all exit paths after the table is acquired through a common
acpi_put_table(). The VBIOS image is copied out with kmemdup() before
the table is released, so it remains valid for the caller.

(cherry picked from commit ca5988682b4cba4cd125a0fa99b2de1239164ae4)

The Linux kernel CVE team has assigned CVE-2026-68238 to this issue.


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

	Fixed in 6.18.42 with commit 312278b3091912fa56a6a587609f17dcb33465c2
	Fixed in 7.1.6 with commit 9b7de3ee5d2c5ee2a706e5f7ca0126f4fbea4da8
	Fixed in 7.2-rc4 with commit 65bff26617607c1331283232016c0e89088c5b78

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-2026-68238
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/gpu/drm/amd/amdgpu/amdgpu_bios.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/312278b3091912fa56a6a587609f17dcb33465c2
	https://git.kernel.org/stable/c/9b7de3ee5d2c5ee2a706e5f7ca0126f4fbea4da8
	https://git.kernel.org/stable/c/65bff26617607c1331283232016c0e89088c5b78