[CVE-2026-68104][MODERATE 7.0] drm/amdgpu: invoke pm_genpd_remove() before freeing genpd

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

CVE: CVE-2026-68104
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/amdgpu: invoke pm_genpd_remove() before freeing genpd
Commit: bdfc7f1e0900ef1361b828c4f69b72701f8a0a86
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bdfc7f1e0900ef1361b828c4f69b72701f8a0a86
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68104
Analysis date: Mon, 10 Aug 2026 13:20:22 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: NO

Summary:
The amdgpu ACP teardown path could free a still registered generic power domain object, leaving a stale genpd pointer that may later be dereferenced by power management code and cause a local kernel crash or possible UAF impact.

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

The original Linux kernel CVE announcement for CVE-2026-68104 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68104

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 7.0
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-2026-68104	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	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-459;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'The amdgpu ACP teardown path could free the acp_genpd object while its generic power domain remained registered in genpd core state. This leaves a stale pointer to freed memory that may be reached later by power management code, making the issue a use after free candidate rather than a simple resource leak. For the CVSS the PR:L is used for the paranoid score because practical triggering may be possible through delegated device management, reduced capability root, or service contexts that can force driver teardown or device recovery. The issue is not network reachable and requires local control over GPU driver or device lifecycle operations. Impact is at least local denial of service via kernel crash and in worst case may allow confidentiality or integrity impact due to stale pointer use after free, so manual review is recommended.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)  SKIP CVE-2026-68104 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	SIMPLEFIX HARDWARE  INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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

ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Memory corruption, weak/indirect corruption candidate: +1
  The patch prevents freeing `acp_genpd` while its embedded generic PM domain remains registered in genpd core state. This is a stale pointer / UAF candidate, but no controlled reclaim, write primitive, or callback hijack is shown.

* Real lifetime corruption: +1
  The bug is a real object lifetime ordering issue: unregister from the global genpd structures must happen before `kfree()`.

* Reliable kernel crash / strong DoS: +1
  A later genpd traversal of the stale domain can plausibly dereference freed memory and crash the kernel.

* Requires admin/root/CAP_* in typical deployments: -2
  The most direct trigger is driver teardown, device removal, module unload, or GPU reset paths, which are normally privileged.

* Privileged kernel/device-management memory corruption path: +1
  The corruption is in GPU driver teardown and power-domain management, a trusted device-management path.

Conservative total: 1 + 1 + 1 - 2 + 1 = 2 to 3. Rounded to 3 because the bug is a real stale registered object, not just a leak.

Paranoid additional interpretation:

* Weak LPE concern: +1
  The stale object is embedded in a generic PM domain structure that can be reached later by kernel power-management code. This is not a demonstrated LPE primitive, but it is more concerning than a pure NULL dereference.

* Reduced-privilege / delegated device-management interpretation: +1 relative to conservative
  In some deployments, a service, container root, reduced-capability root, or delegated device-management context may be able to force reset, teardown, recovery, or hot-unplug-like paths without being full host root.

Paranoid total: 5.

## 3. Reachability analysis

The bug is local and not network reachable. The likely trigger requires control over AMD GPU driver lifecycle operations such as driver unload, device teardown, reset, recovery, or related power-management paths.

In typical deployments this is admin-controlled, so the conservative interpretation treats it as privileged. A paranoid interpretation is still defensible because GPU management may be delegated to service accounts, containerized GPU stacks, or reduced-capability root contexts in some environments.

The path is hardware and driver dependent. It affects systems using the relevant AMDGPU ACP path, not all Linux systems. The bug is not default-exposed to remote attackers.

Call-site confidence: medium. The patch directly shows the lifetime bug in teardown, but the exact later genpd traversal path is not included in the supplied diff.

## 4. Severity interpretation

This is stronger than an ordinary cleanup bug because freeing a still-registered genpd object can leave a stale pointer in global kernel power-management state. Realistic impact is most likely local DoS through a kernel crash during later power-domain activity.

Theoretical memory-corruption risk exists because this is a stale pointer / UAF candidate, but the patch does not show attacker-controlled reclaim, overwrite, type confusion, refcount takeover, or callback control. Therefore it should not be treated as a Strong Important candidate by default.

It fits Actionable Moderate handling. Manual review is justified because lifetime bugs in registered global objects can be underestimated during initial triage.

## 5. One-sentence report phrase

The amdgpu ACP teardown path could free a still registered generic power domain object, leaving a stale genpd pointer that may later be dereferenced by power management code and cause a local kernel crash or possible UAF impact.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is a real lifetime ordering bug with a stale registered object and UAF potential, but no concrete LPE primitive is demonstrated in the patch.

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

Patch: drm/amdgpu: invoke pm_genpd_remove() before freeing genpd
Commit: bdfc7f1e0900ef1361b828c4f69b72701f8a0a86
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bdfc7f1e0900ef1361b828c4f69b72701f8a0a86

Commit description:

Call pm_genpd_remove() to unregister from global list prior to releasing
acp_genpd memory, and clear the pointer after free.

Signed-off-by: Ce Sun <cesun102@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit cd8650d )
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/amd/amdgpu/amdgpu_acp.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=bdfc7f1e0900ef1361b828c4f69b72701f8a0a86

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

The original Linux kernel CVE announcement for CVE-2026-68104 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68104

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:H/UI:N/S:U/C:N/I:N/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: 3
  Paranoid ActionableScore: 5

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 7.0

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).