[CVE-2026-64021][LOW] drm/xe/oa: Fix exec_queue leak on width check in stream open [ Upstream

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

CVE: CVE-2026-64021
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/xe/oa: Fix exec_queue leak on width check in stream open [ Upstream
Commit: 04ef7592eaadd9ca8f8f66e76452f73525cff819
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=04ef7592eaadd9ca8f8f66e76452f73525cff819
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64021
Analysis date: Sun, 19 Jul 2026 22:32:02 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A local DRM xe OA ioctl error path leaks an exec_queue reference after xe_exec_queue_lookup, keeping exec_queue and xe_file private state pinned indefinitely and allowing repeated local triggering to cause resource exhaustion DoS.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-64021 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64021

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: LOW
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-2026-64021	LOW	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:N/I:N/A:H';*CWE-401;*CWE-772;**CWE-400;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'The xe OA stream open path can leak an exec_queue reference when the width check rejects an exec queue after xe_exec_queue_lookup has already taken a reference. The leaked exec_queue also keeps the xe_file private state pinned, and file close cannot release this leaked lookup reference because it is not tracked through the file exec_queue xarray. For the CVSS the PR:L is used because triggering requires local access to the DRM xe device and the relevant OA stream ioctl, but it does not require full administrator privileges in typical GPU render node deployments. The issue is not network reachable and is triggered through a local device ioctl. Impact is denial of service through resource exhaustion if the failing path is repeated. No confidentiality or integrity impact is assigned because the primitive is a reference leak without evidence of UAF, OOB access, arbitrary write, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)  SKIP CVE-2026-64021 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: f0ed39830e6064d62f9c5393505677a26569bb56 YES  NO NO unknown 	MAYBE	SIMPLEFIX LEAK HARDWARE  INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**::

## 2. Signal breakdown

Triggered signals:

* Local unprivileged trigger: +1
  The issue is reachable through a local DRM xe OA ioctl if the user can open the relevant DRM device node and create or reference an exec_queue.

* Availability impact realistic: +1
  The leaked exec_queue reference pins both the exec_queue and xe_file private state indefinitely. Repeated triggering can cause resource exhaustion.

Not awarded:

* No remote reachable signal. This is a local device ioctl path.
* No generic memory corruption. The patch fixes a reference leak, not UAF, OOB access, double free, type confusion, or arbitrary write.
* No privilege escalation signal. There is no reclaim, overwrite, callback control, refcount takeover, or object confusion primitive shown.
* No high-control GPU API bonus. The RDMA/GPU/device-object rule applies because object configuration alone is not enough without evidence of exploitation-relevant memory layout or lifetime control beyond the leak itself.
* No strong DoS bonus. The bug can cause sustained resource exhaustion, but the patch does not show an immediate reliable kernel crash.

## 3. Reachability analysis

A local user or process with access to the Intel xe DRM device and the OA stream open ioctl can potentially trigger the bug by passing an exec_queue whose width is greater than 1. This does not require network access. In typical desktop or GPU compute deployments, DRM render nodes may be accessible to non-root users, so PR:L is the practical CVSS interpretation. Some environments may restrict OA or performance monitoring interfaces through permissions or policy, which reduces exposure but does not change the bug class.

Namespaces or containers matter only if the DRM device node is passed into the container. Without device access, the bug is not reachable. With device access, a containerized user may be able to trigger the same local resource leak against the host kernel.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like local resource leak. The practical impact is local denial of service through pinned kernel objects after repeated failed ioctl calls. There is no evidence of memory corruption, confidentiality impact, integrity impact, or privilege escalation. Theoretical concern is limited to resource exhaustion, not arbitrary kernel object reuse or control-flow manipulation.

## 5. One-sentence report phrase

A local DRM xe OA ioctl error path leaks an exec_queue reference after xe_exec_queue_lookup, keeping exec_queue and xe_file private state pinned indefinitely and allowing repeated local triggering to cause resource exhaustion DoS.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed from security triage unless the affected product exposes xe OA ioctls broadly to untrusted users and has evidence that repeated leaks cause severe host-wide exhaustion. The patch supports a reference leak only, without memory corruption or privilege escalation indicators.

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UPSTREAM PATCH SUMMARY
======================================================================

Patch: drm/xe/oa: Fix exec_queue leak on width check in stream open [ Upstream
Commit: 04ef7592eaadd9ca8f8f66e76452f73525cff819
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=04ef7592eaadd9ca8f8f66e76452f73525cff819

Changed files:
  drivers/gpu/drm/xe/xe_oa.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=04ef7592eaadd9ca8f8f66e76452f73525cff819

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

The original Linux kernel CVE announcement for CVE-2026-64021 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64021

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:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

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: unknown
  Paranoid ActionableScore: 2

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).