[CVE-2026-43195][MODERATE REGULAR] drm/amdgpu: validate user queue size constraints [ Upstream

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

CVE: CVE-2026-43195
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/amdgpu: validate user queue size constraints [ Upstream
Commit: cf2a37be899dc1b01f53bf1d0157330eaf3e3f55
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cf2a37be899dc1b01f53bf1d0157330eaf3e3f55
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43195
Analysis date: Sat, 01 Aug 2026 13:02:49 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
AMDGPU user queue creation failed to validate that queue_size is a power of two and at least AMDGPU_GPU_PAGE_SIZE, allowing a local GPU user to submit invalid queue parameters that may cause GPU faults or degraded GPU availability.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-43195 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43195

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 REGULAR
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-2026-43195	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:N/I:N/A:H';*CWE-20;CWE-1284;**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 'AMDGPU user queue creation did not validate that the queue size is a power of 2 and at least AMDGPU_GPU_PAGE_SIZE. Invalid sizes can break ring buffer wrapping assumptions or create undersized queue configurations, which may lead to GPU faults or unexpected device behavior. For the CVSS the PR:L is used for the paranoid score because local DRM render node or GPU device access may be available to non root users in common desktop and compute deployments. The issue is not network reachable and requires local access to the AMDGPU user queue interface. Impact is primarily denial of service through GPU fault, reset, or degraded GPU availability. No concrete kernel memory corruption or privilege escalation primitive is visible from the patch context.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 3)  SKIP CVE-2026-43195  SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	HARDWARE MEMORY  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Borderline, manual review recommended**::

## 2. Signal breakdown

Triggered signals:

* Local unprivileged trigger: +1
  AMDGPU DRM render nodes or GPU device interfaces are commonly reachable by local non-root users in desktop and compute deployments.

* Availability impact realistic: +1
  The commit explicitly mentions GPU faults or unexpected behavior. This supports local GPU DoS, reset, or degraded GPU availability, but not a proven host-wide kernel crash.

* Broad/default/common subsystem or broadly deployed exposure: +1 for paranoid score only
  AMDGPU is a common DRM driver on affected hardware, and user queue creation is a realistic local GPU interface. This is hardware-dependent, so I count it only in the paranoid score.

Not triggered:

* Generic memory corruption: +0
  The patch only adds input validation for queue_size. It does not show UAF, OOB write, double free, type confusion, refcount misuse, or arbitrary write.

* Privilege escalation plausible: +0
  No concrete LPE primitive is visible from the patch.

* High-control kernel data-plane API: +0
  This is a rich device API, but the patch does not show attacker control over kernel object lifetime, callbacks, refcounts, DMA mappings, or page ownership.

* Reliable kernel crash / strong DoS: +0
  The described failure is GPU faults or unexpected behavior, not a demonstrated kernel panic or reliable system-wide crash.

Caps and constraints:

* Validation-only unspecified-corruption cap applies. Conservative score should remain at or below 4 and paranoid score at or below 5.
* The patch rejects invalid input with EINVAL and does not describe a downstream corruption primitive.

## 3. Reachability analysis

A local user with access to the AMDGPU user queue interface can potentially trigger the invalid queue_size path. In typical systems this may include non-root users with access to DRM render nodes or GPU compute interfaces.

This is not network reachable. Containers may matter if GPU devices are passed through or render nodes are exposed into the container. If the device node is not accessible to untrusted users, practical reachability is much lower.

The affected path is hardware and driver dependent. It is relevant on AMDGPU systems that expose user queues, but it is not a generic kernel-wide path.

Call-site confidence: medium. The validation function and immediate rejected fields are visible, but the deeper hardware fault behavior is described only at a high level.

## 4. Severity interpretation

This behaves more like a low-to-moderate local device DoS than an Important-class kernel vulnerability. The theoretical concern is that invalid queue sizes can violate hardware ring buffer assumptions or cause undersized allocations, but the patch does not show a memory corruption primitive in kernel memory.

Realistic impact is GPU fault, reset, or degraded GPU availability. There is not enough evidence for confidentiality impact, integrity impact, or privilege escalation.

## 5. One-sentence report phrase

AMDGPU user queue creation failed to validate that queue_size is a power of two and at least AMDGPU_GPU_PAGE_SIZE, allowing a local GPU user to submit invalid queue parameters that may cause GPU faults or degraded GPU availability.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is probably not Important and should not be treated as proven memory corruption, but manual confirmation is useful because local render node users may be unprivileged and the exact GPU fault behavior depends on hardware and queue handling.

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

Patch: drm/amdgpu: validate user queue size constraints [ Upstream
Commit: cf2a37be899dc1b01f53bf1d0157330eaf3e3f55
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cf2a37be899dc1b01f53bf1d0157330eaf3e3f55

Changed files:
  drivers/gpu/drm/amd/amdgpu/amdgpu_userq.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=cf2a37be899dc1b01f53bf1d0157330eaf3e3f55

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

The original Linux kernel CVE announcement for CVE-2026-43195 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43195

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: 2
  Paranoid ActionableScore: 3

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 REGULAR

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).