[CVE-2025-71315][LOW] drm/vkms: Convert to DRM's vblank timer [ Upstream

[CVE-2025-71315][LOW] drm/vkms: Convert to DRM's vblank timer [ Upstream

[AL-KERNEL]

CVE: CVE-2025-71315
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/vkms: Convert to DRM's vblank timer [ Upstream
Commit: a0582cc923985c6b72fe871b5f7aa7c682bfc230
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a0582cc923985c6b72fe871b5f7aa7c682bfc230
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-71315
Analysis date: Mon, 06 Jul 2026 20:15:59 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2025-71315 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-71315

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.

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

CVE-2025-71315	LOW	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:N';BEST CVSS score: '2.5';DESCR 'This change converts VKMS from a private hrtimer based vblank simulation path to the generic DRM vblank timer helpers. No clear vulnerability primitive is shown by the diff. There is no explicit UAF, OOB access, NULL dereference, information leak, or privilege escalation path in the patch context. For the CVSS the PR:L is only a conservative local access assumption for interacting with a DRM device or test setup, but the base security impact is effectively none. The issue is not network reachable. Impact is best treated as non security or at most a low availability risk if the old timer code could misbehave in a local VKMS test environment.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 0) 	YES	DANGER INIT SIMPLEFIX RACE DMAorINTERRUPT TIMER HARDWARE LINUS MEMORY  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	checked

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

ActionableScore=0

1. **ActionableScore**
* Conservative score: 0
* Paranoid score: 0
* Final recommended bucket: **Ordinary Moderate / Low-like**::

2. **Signal breakdown**
* No remote reachable / network-triggerable path: +0. VKMS is a local virtual DRM driver path, not a network protocol.
* No local unprivileged trigger with security impact: +0. Local DRM interaction may be possible in test setups, but the patch does not show a vulnerability primitive.
* No privilege escalation plausible: +0. No UAF, overwrite, type confusion, refcount abuse, stale callback, or object replacement is shown.
* No generic memory corruption: +0. The diff is a refactor from a private hrtimer to DRM vblank timer helpers.
* No real lifetime corruption: +0. Removing a custom hrtimer does not by itself demonstrate a stale timer callback or use-after-free.
* Reliable kernel crash / strong DoS: +0. The commit does not describe a crash, panic, Oops, hang, or reproducible DoS.
* Availability impact realistic: +0. At most this suggests possible correctness or timer behavior cleanup in VKMS, not a demonstrated availability vulnerability.
* Rare/test-oriented subsystem: -1 conceptually, but score is clamped at 0. VKMS is mainly used for virtual display testing and CI rather than broad production exposure.

3. **Reachability analysis**
The affected path is local to the VKMS DRM driver. A user would need access to a system where VKMS is loaded and usable through local DRM interfaces. There is no network exposure and no firmware-mediated input. Namespace or container behavior does not materially increase severity unless a container is explicitly granted access to the VKMS DRM device, and even then the patch does not show a concrete security failure. The path is not a default high-risk kernel attack surface on typical production systems.

4. **Severity interpretation**
This behaves like a non-security refactor or, at most, a Low-like local availability concern. Theoretical risk from timer refactoring exists only as a generic possibility, but the provided patch does not demonstrate memory corruption, information disclosure, privilege escalation, or a reliable crash. It should not be treated as an actionable Moderate or Important-class kernel vulnerability.

5. **One-sentence report phrase**
This VKMS change replaces a private vblank hrtimer implementation with DRM generic vblank timer helpers, with no concrete vulnerability primitive or realistic security impact shown by the patch.

6. **Manual review recommendation**
NO MANUAL CHECK NEEDED. The patch has no Fixes tag, no described crash, no memory lifetime primitive, no network exposure, and no plausible privilege escalation path from the provided context.

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

Patch: drm/vkms: Convert to DRM's vblank timer [ Upstream
Commit: a0582cc923985c6b72fe871b5f7aa7c682bfc230
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a0582cc923985c6b72fe871b5f7aa7c682bfc230

Changed files:
  drivers/gpu/drm/vkms/vkms_crtc.c
  drivers/gpu/drm/vkms/vkms_drv.h

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=a0582cc923985c6b72fe871b5f7aa7c682bfc230

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

The original Linux kernel CVE announcement for CVE-2025-71315 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-71315

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:N/I:N/A:N
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS score: 2.5

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: 0

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).