[CVE-2026-23163][MODERATE REGULAR] drm/amdgpu: fix NULL pointer dereference in amdgpu_gmc_filter_faults_remove [ Upstream

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

CVE: CVE-2026-23163
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/amdgpu: fix NULL pointer dereference in amdgpu_gmc_filter_faults_remove [ Upstream
Commit: c74e2dbb5316898fb2113a8ea3a93b27698dbf68
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c74e2dbb5316898fb2113a8ea3a93b27698dbf68
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-23163
Analysis date: Sat, 01 Aug 2026 13:50:51 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline Moderate, manual review recommended but not Important
Manual review required: YES

Summary:
A local user with access to affected AMDGPU APU SVM functionality may trigger a NULL pointer dereference in retry fault recovery, causing a kernel crash without evidence of privilege escalation or data disclosure.

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

The original Linux kernel CVE announcement for CVE-2026-23163 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-23163

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.

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

CVE-2026-23163	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	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-476;CWE-703;CWE-754;BEST CVSS score: '5.5';DESCR 'A NULL pointer dereference in the amdgpu SVM retry fault recovery path can occur on AMD APUs where secondary IH rings such as ih1 are not initialized by design. amdgpu_gmc_filter_faults_remove() used ih1 unconditionally and could pass an invalid interrupt ring to helper code when retry faults are enabled, causing a kernel crash during GPU page fault handling. For the CVSS the PR:L is used because an attacker needs local code execution or access to GPU device nodes to generate SVM GPU page faults, but full administrative privileges are not required in common render group deployments. The issue is not network reachable and depends on affected APU hardware and retry fault handling being active. Impact is denial of service via kernel crash. No evidence of UAF, OOB access with attacker controlled overwrite, information disclosure, or privilege escalation primitive is visible from the patch context.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline Moderate, manual review recommended but not Important (with actual score 3)  SKIP CVE-2026-23163  SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	DANGER NULLPTR HARDWARE  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Borderline Moderate, manual review recommended but not Important**

## 2. Signal breakdown

Triggered signals:

* Local unprivileged trigger: +1
  Local users with access to AMD GPU render nodes may be able to trigger SVM GPU page fault handling without full root privileges.

* Reliable kernel crash / strong DoS: +1
  The commit shows a concrete NULL pointer dereference in `amdgpu_ih_decode_iv_ts_helper()` leading to a kernel crash path.

Paranoid-only signal:

* Broad/default/common subsystem or broadly deployed exposure: +1
  AMDGPU is a commonly deployed desktop and workstation GPU driver, and affected APUs such as Raven and Renoir are not exotic. This is exposure-based only, not an added exploit primitive.

Not applied:

* Generic memory corruption: +0
  The demonstrated primitive is a NULL pointer dereference, not UAF, OOB write, double free, type confusion, or arbitrary write.

* Privilege escalation plausible: +0
  No reclaim, overwrite, stale callback, refcount abuse, or attacker-controlled object replacement is shown.

* Confidentiality / Integrity impact: +0
  No information disclosure or data modification primitive is visible.

* Remote reachable: +0
  This is a local GPU fault recovery path, not network reachable.

* Rare hardware-only condition: 0
  The issue is hardware-specific, but affected AMD APUs are common enough that I would not subtract the full rare-hardware penalty.

## 3. Reachability analysis

The likely trigger is a local process using GPU/SVM functionality on affected AMD APUs where secondary IH rings are absent and retry faults are enabled. In typical systems, GPU render node access may be available to non-root users in the render or video group, so PR:L is the practical assumption. Containers may inherit GPU device access if `/dev/dri` nodes are passed through, but this is deployment-dependent.

The path is not remotely reachable. It depends on affected APU generations and the `noretry=0` retry-fault configuration, which became exposed by the referenced change for Renoir.

Call-site confidence: high. The commit includes the crash stack and the direct faulty call path.

## 4. Severity interpretation

This behaves like an ordinary to borderline Moderate local DoS. The theoretical impact is limited by the demonstrated primitive: a NULL pointer dereference in an interrupt/fault handling path. There is no evidence of UAF, OOB write, stale object reuse, callback control, or privilege escalation.

The paranoid score is raised only for practical deployment exposure of AMDGPU on common APUs, not because the bug shows memory corruption or LPE potential.

## 5. One-sentence report phrase

A local user with access to affected AMDGPU APU SVM functionality may trigger a NULL pointer dereference in retry fault recovery, causing a kernel crash without evidence of privilege escalation or data disclosure.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Manual review is useful to confirm whether affected products expose AMDGPU render nodes to untrusted users and whether affected APU generations run with retry fault handling enabled. This does not look like an Important-class vulnerability from the patch context.

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

Patch: drm/amdgpu: fix NULL pointer dereference in amdgpu_gmc_filter_faults_remove [ Upstream
Commit: c74e2dbb5316898fb2113a8ea3a93b27698dbf68
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c74e2dbb5316898fb2113a8ea3a93b27698dbf68

Changed files:
  drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.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=c74e2dbb5316898fb2113a8ea3a93b27698dbf68

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

The original Linux kernel CVE announcement for CVE-2026-23163 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-23163

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: Not available
  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).