[CVE-2026-68265][MODERATE 7.0] drm/xe/vm: Fix BO prefetch with CONSULT_MEM_ADVISE_PREF_LOC [ Upstream

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-68265
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/xe/vm: Fix BO prefetch with CONSULT_MEM_ADVISE_PREF_LOC [ Upstream
Commit: d256dac008d1d9e6378aa1a5454e89a8292d174c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d256dac008d1d9e6378aa1a5454e89a8292d174c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68265
Analysis date: Mon, 10 Aug 2026 13:55:40 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: NO

Summary:
A local user with access to the Xe DRM device can trigger an OOB read by causing DRM_XE_CONSULT_MEM_ADVISE_PREF_LOC to be used as a negative region_to_mem_type index in the BO prefetch path, leading primarily to kernel or GPU driver DoS with limited paranoid integrity concern due to the value being consumed by BO migration.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-68265 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68265

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: MODERATE 7.0
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-68265	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H';CWE-125;CWE-129;**CWE-476;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.6';DESCR 'An out of bounds read in the drm xe VM prefetch path occurs when DRM_XE_CONSULT_MEM_ADVISE_PREF_LOC has value -1 and is used as an index into region_to_mem_type for a BO VMA. A local process with access to the Xe DRM device can trigger this through VM prefetch and memory advise state, causing an invalid memory type selection and potentially a NULL pointer dereference or kernel crash. For the CVSS the PR:L is used because triggering requires local access to the DRM Xe device node or delegated GPU access, not full administrator privileges. The issue is not network reachable. Impact is primarily denial of service, but the paranoid score keeps limited confidentiality and integrity impact because the bug is an out of bounds kernel read whose result is consumed by a migration path.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)  SKIP CVE-2026-68265 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: c1bb69a2e8e2d55c3725e304d8b8fd189ee43fbe YES  NO NO unknown 	MAYBE	OOB NULLPTR HARDWARE  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1
  The affected path is a DRM Xe VM prefetch path. A local process with access to the Xe DRM device node can plausibly reach it without full host root.

* Memory corruption, weak/indirect corruption candidate: +1
  The bug is an unchecked negative index. DRM_XE_CONSULT_MEM_ADVISE_PREF_LOC is -1 and was used as an index into region_to_mem_type. This is an OOB read, not an OOB write.

* Reliable kernel crash / strong DoS: +1
  The commit explicitly mentions OOB access and v2 says Fix null dereference. The invalid mem_type can feed xe_bo_migrate and plausibly crash the kernel or GPU driver path.

Paranoid additional signals:

* Integrity impact plausible: +1
  The OOB-read result is not only read and discarded. It is consumed as a memory type for BO migration, so a wrong object placement or migration decision is plausible, although no controlled write primitive is shown.

* Privileged device memory-management path: +1
  The corrupted decision occurs in a GPU VM and BO migration path, which is a trusted device memory-management context. This is not enough for Important by itself, but it makes the bug actionable for manual review.

Not counted:

* Remote/network reachable: +0
  No network path is involved.

* Strong LPE plausibility: +0
  No attacker-controlled overwrite, reclaim, type confusion, callback control, refcount takeover, or arbitrary write is shown.

* Confidentiality impact: +0 conservative
  The OOB read is not shown to be disclosed to userspace.

Call-site confidence: medium. The changed call into xe_bo_migrate is visible, but the full ioctl and userspace trigger path is not included.

## 3. Reachability analysis

The likely trigger is a local process that can access the Intel Xe DRM device and issue VM prefetch or related memory-advice operations. In common desktop or GPU-enabled server configurations, render nodes may be available to non-root users or to workloads granted GPU access, so PR:L is more appropriate than PR:H.

Containers matter if the Xe DRM device is passed through. A container without GPU device access cannot normally trigger it, but a container or service account with delegated render node access may be able to reach the path without full host-root privileges.

The path is not network reachable. It depends on Xe driver availability and relevant BO VMA prefetch behavior. This is more specific than a core kernel path, but not rare enough to auto-close when affected hardware and driver are present.

## 4. Severity interpretation

This behaves like an actionable Moderate issue rather than an ordinary Low/Moderate cleanup. The realistic impact is primarily local DoS through an OOB access or NULL dereference in a GPU kernel driver path.

The theoretical concern is limited kernel memory misuse because a negative array index feeds a BO migration decision. However, the patch does not show an arbitrary write, attacker-controlled target selection, controlled payload, UAF reclaim, or type confusion. Therefore it should not be treated as a strong Important candidate solely from the patch, but it should not be auto-closed without manual review.

## 5. One-sentence report phrase

A local user with access to the Xe DRM device can trigger an OOB read by causing DRM_XE_CONSULT_MEM_ADVISE_PREF_LOC to be used as a negative region_to_mem_type index in the BO prefetch path, leading primarily to kernel or GPU driver DoS with limited paranoid integrity concern due to the value being consumed by BO migration.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is a local DRM driver OOB access with a visible downstream use in xe_bo_migrate. It is not enough for a strong LPE classification from the patch alone, but the GPU VM and BO migration context makes it unsafe to auto-close.

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UPSTREAM PATCH SUMMARY
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Patch: drm/xe/vm: Fix BO prefetch with CONSULT_MEM_ADVISE_PREF_LOC [ Upstream
Commit: d256dac008d1d9e6378aa1a5454e89a8292d174c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d256dac008d1d9e6378aa1a5454e89a8292d174c

Changed files:
  drivers/gpu/drm/xe/xe_vm.c

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d256dac008d1d9e6378aa1a5454e89a8292d174c

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DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-68265 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68265

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 6.6

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: 3
  Paranoid ActionableScore: 5

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE 7.0

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).