CVE-2026-68265: drm/xe/vm: Fix BO prefetch with CONSULT_MEM_ADVISE_PREF_LOC

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

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

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

drm/xe/vm: Fix BO prefetch with CONSULT_MEM_ADVISE_PREF_LOC

When prefetch region is DRM_XE_CONSULT_MEM_ADVISE_PREF_LOC for a BO VMA,
the code used it as an index into region_to_mem_type[], causing an
out-of-bounds access since the value is -1.

Resolve the preferred location for BO VMAs directly: local VRAM on dGFX
(using the BO's tile placement) or system memory on iGPU.

Discovered using AI-assisted static analysis confirmed by Intel Product
Security.

v2:
-Fix null dereference

(cherry picked from commit d9a4906ac03be9f6ed3f3b45c56c866b867fd75b)

The Linux kernel CVE team has assigned CVE-2026-68265 to this issue.


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

	Issue introduced in 6.18 with commit c1bb69a2e8e2d55c3725e304d8b8fd189ee43fbe and fixed in 6.18.44 with commit d256dac008d1d9e6378aa1a5454e89a8292d174c
	Issue introduced in 6.18 with commit c1bb69a2e8e2d55c3725e304d8b8fd189ee43fbe and fixed in 7.1.6 with commit c4affa4e8bc8086b4d3e8d6cf1055a624f813d72
	Issue introduced in 6.18 with commit c1bb69a2e8e2d55c3725e304d8b8fd189ee43fbe and fixed in 7.2-rc4 with commit 7bc597ce74bab4153b2009c92eccf889e9d74044

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-2026-68265
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/xe/xe_vm.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/d256dac008d1d9e6378aa1a5454e89a8292d174c
	https://git.kernel.org/stable/c/c4affa4e8bc8086b4d3e8d6cf1055a624f813d72
	https://git.kernel.org/stable/c/7bc597ce74bab4153b2009c92eccf889e9d74044