[CVE-2026-74440][MODERATE 7.0] drm/xe: Wait on external BO kernel fences in exec IOCTL [ Upstream

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

CVE: CVE-2026-74440
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: drm/xe: Wait on external BO kernel fences in exec IOCTL [ Upstream
Commit: 1738db550334adca0e7fcf0ef684198fb7462779
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1738db550334adca0e7fcf0ef684198fb7462779
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74440
Analysis date: Sat, 15 Aug 2026 10:28:11 -0400
ActionableScore: 7
ActionableScore lower bound: 5
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A missing wait on external BO dma-resv KERNEL fences in drm/xe exec submission can let a local render-node user race GPU jobs against BO eviction or move operations, potentially causing DoS and possible confidentiality or integrity impact through access to memory while it is being migrated.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-74440 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74440

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: YES

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-2026-74440	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';CWE-362;CWE-667;*CWE-664;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'drm xe exec ioctl could arm a user GPU job after waiting only on the VM dma resv KERNEL slot while skipping KERNEL fences on external BOs. External BOs carry eviction, move, and other memory management operations in their own dma resv KERNEL slots, so a submitted job could race those kernel operations and access BO memory while it is being moved. For the CVSS the PR:L value is used because a local user or process with access to the DRM render node can submit exec ioctls in typical deployments. The issue is not directly network reachable and requires local GPU driver access. Impact is at least denial of service or GPU memory corruption, and the worst defensible interpretation includes confidentiality and integrity impact because the race can involve reading or writing memory during BO migration.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7)	YES	HARDWARE KPANIC MEMORY  KPANIC INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN6 DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=7
ActionableScoreLower=5

## 1. ActionableScore

* Conservative score: 5
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. `xe_exec_ioctl()` is reachable by a local process with access to the DRM render node in typical GPU deployments.
* Memory corruption, weak/indirect corruption candidate: +1. The bug allows a user GPU job to race kernel BO move or eviction operations and potentially access memory while it is being migrated, but the patch does not show a controlled arbitrary write primitive.
* Privileged kernel/device-management memory corruption path: +1. The race is in GPU memory management and dma-resv synchronization, involving trusted kernel/device operations on BO backing storage.
* Reliable kernel crash / strong DoS: +1. Racing user execution against BO migration can plausibly cause GPU fault, device hang, or kernel-visible memory-management failure.
* Confidentiality impact plausible: +1. The commit explicitly mentions potentially reading memory while it is being moved.
* Integrity impact plausible: +1. The commit explicitly mentions potentially writing memory while it is being moved.
* Hard or unreliable race / special timing required: -1. Triggering depends on overlap between exec submission and external BO kernel operations such as eviction or move.

Conservative total: 5.

Paranoid additions / interpretation:

* Weak LPE concern: +1. The read/write race during BO migration may cross GPU memory-management boundaries, but there is no demonstrated reclaim, arbitrary write, or reliable object confusion primitive.
* Broad/default/common subsystem exposure: +1. DRM render nodes and GPU exec ioctls are common on affected desktop, workstation, and compute systems using Intel Xe.

Paranoid total: 7.

## 3. Reachability analysis

The bug is local, not network reachable. A local user or process with access to the Intel Xe DRM render node can submit exec ioctls and use BOs mapped into a VM. In many distributions, render node access is available to users in the `render` or similar group, so this should be treated as PR:L rather than PR:H.

Namespaces and containers may matter if GPU device nodes are passed through to containers. A containerized or reduced-privilege workload with render node access could potentially reach the ioctl without full host root privileges.

The path is not universal to all Linux systems, but it is a normal GPU driver execution path for affected Intel Xe deployments. Realistic triggering likely requires arranging external BOs plus concurrent eviction, defrag, or move activity, so the race is not a trivial one-shot trigger.

## 4. Severity interpretation

This is more than an ordinary Moderate correctness issue because the violated dma-resv KERNEL fence contract can let a user GPU job run concurrently with kernel memory-management operations on external BOs. The realistic evidence supports at least Actionable Moderate handling due to possible GPU memory corruption and DoS.

The Important-class interpretation is defensible for manual triage because the commit explicitly describes potential reads or writes of memory while it is being moved. However, the patch does not demonstrate a controlled arbitrary write, attacker-controlled reclaim, type confusion, or a reliable privilege-escalation primitive. Therefore the conservative score remains 5, while the paranoid/manual-review score is 7.

## 5. One-sentence report phrase

A missing wait on external BO dma-resv KERNEL fences in drm/xe exec submission can let a local render-node user race GPU jobs against BO eviction or move operations, potentially causing DoS and possible confidentiality or integrity impact through access to memory while it is being migrated.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the patch concerns a GPU memory-management race with explicit potential read/write access during BO migration. It is not proven LPE, but the affected primitive is strong enough for manual review and should not be auto-closed.

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UPSTREAM PATCH SUMMARY
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Patch: drm/xe: Wait on external BO kernel fences in exec IOCTL [ Upstream
Commit: 1738db550334adca0e7fcf0ef684198fb7462779
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1738db550334adca0e7fcf0ef684198fb7462779

Changed files:
  drivers/gpu/drm/xe/xe_exec.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=1738db550334adca0e7fcf0ef684198fb7462779

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

The original Linux kernel CVE announcement for CVE-2026-74440 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74440

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:H/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7

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: 5
  Paranoid ActionableScore: 7

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: YES
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).