[CVE-2026-97426][LOW] drm/amdgpu/pm: fix SmartShift bias sysfs store PM refcount on parse error [ Upstream

[CVE-2026-97426][LOW] drm/amdgpu/pm: fix SmartShift bias sysfs store PM refcount on parse error [ Upstream

[AL-KERNEL]

CVE: CVE-2026-97426
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amdgpu/pm: fix SmartShift bias sysfs store PM refcount on parse error [ Upstream
Commit: 95e13b25196295654563028861e6802807006ad4
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=95e13b25196295654563028861e6802807006ad4
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97426
Analysis date: Thu, 24 Sep 2026 17:37:26 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-97426 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97426

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-2026-97426	LOW	https://www.kernelcve.org/list/?q=CVE-2026-97426 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-911;CWE-754;CWE-404;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'The SmartShift bias sysfs store handler called amdgpu_pm_put_access after a numeric parse error even though amdgpu_pm_get_access had not been called. Repeated malformed writes could therefore unbalance the runtime PM reference count and may cause warnings, premature GPU power state changes, or loss of GPU availability. The issue requires local write access to the affected sysfs attribute and is not network reachable. For the CVSS the PR:L in the paranoid score represents deployments where GPU management access is delegated to a local service, device group, container, or reduced capability administrative account. The realistic base case uses PR:H because the attribute is normally writable only by an administrator. Impact is limited to availability because the affected path provides no UAF, OOB access, information disclosure, or arbitrary write primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)  SKIP CVE-2026-97426 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	HARDWARE  INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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

ActionableScore=1
ActionableScoreLower=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 0.
* Conservative score: 0. No floor or cap applied.
* Raw paranoid score: 1.
* Paranoid score: 1. No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

Conservative signals:

* +0 PM accounting mismatch. The parse-error path performs `amdgpu_pm_put_access()` without a matching `amdgpu_pm_get_access()`, but this is runtime power-management accounting rather than an object-lifetime reference that can free `adev`.
* +0 Reliable kernel crash. No crash, panic, UAF, or fatal dereference is established.
* +0 Resource leak. The bug performs an unmatched put rather than losing an acquired reference.
* +0 Privilege penalty. Write permissions for this exact sysfs attribute are not supplied, so host-admin access cannot be positively established.

Paranoid signals:

* +1 Availability impact. Repeated malformed writes can defensibly unbalance runtime PM accounting and potentially cause premature GPU power transitions or device-local GPU unavailability.

Important non-awarded signals:

* No UAF or concrete repeated release of an object whose lifetime may have ended.
* No controlled reclaim, arbitrary write, OOB access, disclosure, or authorization bypass.
* No strong host-wide DoS or kernel crash is established.
* No remote reachability.
* No confidentiality or integrity points.
* No extra availability point because persistent or host-wide failure is not demonstrated.
* No hardware penalty. AMDGPU SmartShift hardware is required, but the evidence does not establish that it is sufficiently rare to justify a deduction.

Repeated-release assessment:

* A first object-lifetime release that can destroy the object is not present.
* No dangling object reference survives an earlier lifetime-ending operation.
* The unmatched PM put changes runtime PM accounting but is not shown to free the `amdgpu_device`.
* Concrete repeated release/refcount +1 was not awarded.
* Paranoid repeated-refcount leverage +1 was not awarded.
* Real UAF FLOOR 5 does not apply.

3. Reachability analysis

The trigger is a malformed local write to the SmartShift bias sysfs attribute on a compatible AMDGPU device. The supplied context does not show the attribute mode, ownership, or an authorization path proving that host-administrator privilege is mandatory. It also does not establish ordinary-user access, so `HostAdminRequired=UNKNOWN`.

A delegated graphics service or modified sysfs permissions could potentially provide below-host-admin write access, but this is not established and receives no reachability bonus. The operation targets a host physical device through global sysfs and is not an attacker-created namespace-scoped object, so `NamespaceScopedPrivilege=NO`.

Compatible AMD GPU and SmartShift support are prerequisites. There is no race or timing requirement. Repeated invalid writes are straightforward once write access exists. The issue is not network reachable.

4. Primitive and severity interpretation

The exact primitive is an unmatched runtime PM put on the numeric parse-error path. It can decrement or otherwise disturb PM access accounting without a corresponding acquisition.

This is not an active-object UAF, fixed stale-storage UAF, double free, or repeated lifetime mutation through a dangling reference. `amdgpu_pm_put_access()` operates on device power-management accounting, and the supplied evidence does not show that it can destroy `adev` or another referenced object.

The demonstrated defect is invalid PM accounting. The defensible worst case is device-local availability degradation through incorrect GPU power-state management. Kernel memory corruption, host-wide failure, and privilege escalation are speculative and unsupported.

`PrimitiveClass=CLASS_C` reflects invalid-state and possible device-DoS behavior without an independently useful corruption primitive. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` are appropriate because no unresolved lifetime, ownership, authorization, or memory-corruption mechanism remains.

5. One-sentence report phrase

A malformed SmartShift bias sysfs write can execute an unmatched runtime PM put and unbalance GPU power management accounting, but the supplied evidence supports at most device-local availability impact without UAF, memory corruption, or privilege escalation.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch fixes a narrow PM accounting error with no established kernel-corruption or security-boundary primitive, so normal deferred patch handling is reasonable.

7. Call-site confidence

Call-site confidence: medium

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

Patch: drm/amdgpu/pm: fix SmartShift bias sysfs store PM refcount on parse error [ Upstream
Commit: 95e13b25196295654563028861e6802807006ad4
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=95e13b25196295654563028861e6802807006ad4

Changed files:
  drivers/gpu/drm/amd/pm/amdgpu_pm.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=95e13b25196295654563028861e6802807006ad4

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

The original Linux kernel CVE announcement for CVE-2026-97426 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97426

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:H/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: 0
  Paranoid ActionableScore: 1

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).