[CVE-2026-52976][IMPORTANT] drm/xe: Fix error cleanup in xe_exec_queue_create_ioctl() [ Upstream

[CVE-2026-52976][IMPORTANT] drm/xe: Fix error cleanup in xe_exec_queue_create_ioctl() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-52976
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: drm/xe: Fix error cleanup in xe_exec_queue_create_ioctl() [ Upstream
Commit: f93b00161213a0fe9f7ff1d8498ee5ca9e0a5c43
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f93b00161213a0fe9f7ff1d8498ee5ca9e0a5c43
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52976
Analysis date: Thu, 25 Jun 2026 11:10:38 -0400
ActionableScore: 7
ActionableScore lower bound: 5
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A use-after-free in the drm/xe exec queue creation ioctl can leave a freed queue linked in VM or hardware engine group lists after error cleanup, allowing a local user with DRM device access to trigger at least a kernel crash and possibly memory-corruption impact.

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ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-52976 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52976

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: IMPORTANT
Manual review required: YES

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

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-52976	IMPORTANT	CHECK	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-416;*CWE-672;CWE-703;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A use-after-free can occur in the drm/xe exec queue creation ioctl because some error paths free an exec queue while it may still be linked from the VM compute queue list or the hw engine group list. A local process that can issue the XE DRM ioctl may trigger the bug by forcing failures during exec queue creation, leaving a dangling pointer that can later be reached by driver list traversal. For the CVSS the PR:L is used because DRM render nodes are commonly available to local users or render group members rather than requiring full administrator privileges. The issue is not network reachable and requires local code execution on the target. Impact is at least a local denial of service via kernel crash and in worst case may allow confidentiality and integrity impact due to kernel use-after-free memory corruption.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7) 	MAYBE	DANGER ERRORPATH UAF HARDWARE KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7	-	-	checked

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ACTIONABLESCORE ANALYSIS
======================================================================

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

* **Local unprivileged trigger: +1**. The affected path is a DRM XE ioctl, and DRM render nodes are commonly reachable by local users or render group members.
* **Generic memory corruption, strong primitive: +2**. The commit explicitly describes a freed exec queue remaining linked in VM or hardware engine group lists, causing use-after-free.
* **Real lifetime corruption: +1**. This is a stale pointer after free caused by incomplete cleanup on error paths.
* **Reliable kernel crash / strong DoS: +1**. Later traversal of the stale list entry can plausibly dereference freed memory and crash the kernel.
* **Weak LPE concern, conservative: +1**. A dangling kernel object pointer in a driver list may be exploitable beyond DoS, but the patch does not show a controlled reclaim or overwrite primitive.
* **Strong LPE plausibility, paranoid: +2**. In the higher score, the UAF is treated as potentially exploitable because the freed object remains reachable from driver-managed lists and the API is local user controlled.
* **Hard or unreliable trigger condition: -1**. Triggering requires hitting specific error paths such as xe_hw_engine_group_add_exec_queue failure or xa_alloc failure after partial registration.

Conservative total: **1 + 2 + 1 + 1 + 1 - 1 = 5**
Paranoid total: **1 + 2 + 1 + 1 + 2 = 7**

## 3. Reachability analysis

A local process with access to the XE DRM device can reach the vulnerable ioctl. This typically does not require full root privileges on systems where render nodes are exposed to users or GPU workloads. Containers may also be affected if the DRM render device is passed through. The issue is not network reachable. Practical triggering depends on forcing or naturally hitting allocation or registration failures during exec queue creation, so exploit reliability is not guaranteed.

## 4. Severity interpretation

This is stronger than an ordinary Moderate because it is an explicit UAF, not only a warning or cleanup leak. Conservative handling is **Actionable Moderate** due to local reachability and real lifetime corruption. The paranoid interpretation is a **Strong Important candidate** because stale pointers in kernel driver lists can sometimes become privilege escalation primitives, even though this patch alone does not demonstrate reliable object reclaim or controlled corruption.

## 5. One-sentence report phrase

A use-after-free in the drm/xe exec queue creation ioctl can leave a freed queue linked in VM or hardware engine group lists after error cleanup, allowing a local user with DRM device access to trigger at least a kernel crash and possibly memory-corruption impact.

## 6. Manual review recommendation

**MANUAL CHECK REQUIRED**

This should not be auto-closed because the patch fixes an explicit UAF reachable through a local high-control GPU ioctl path, with plausible but unproven privilege-escalation potential.

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

Patch: drm/xe: Fix error cleanup in xe_exec_queue_create_ioctl() [ Upstream
Commit: f93b00161213a0fe9f7ff1d8498ee5ca9e0a5c43
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f93b00161213a0fe9f7ff1d8498ee5ca9e0a5c43

Changed files:
  drivers/gpu/drm/xe/xe_exec_queue.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=f93b00161213a0fe9f7ff1d8498ee5ca9e0a5c43

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

The original Linux kernel CVE announcement for CVE-2026-52976 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52976

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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).