[CVE-2026-98894][LOW] drm/amd/ras: reset CPER ring on corrupt entry size [ Upstream

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

CVE: CVE-2026-98894
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amd/ras: reset CPER ring on corrupt entry size [ Upstream
Commit: a98d0d49757a113ce17960262b9cd4ccc1420108
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a98d0d49757a113ce17960262b9cd4ccc1420108
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98894
Analysis date: Tue, 27 Oct 2026 02:53:32 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
Corrupt AMDGPU CPER entry sizing can stall ring overflow recovery under its mutex, but no memory-corruption or host-wide crash primitive is demonstrated.

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

The original Linux kernel CVE announcement for CVE-2026-98894 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98894

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-2026-98894	LOW	https://www.kernelcve.org/list/?q=CVE-2026-98894 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT LOW AEGIS_AS=1 LEGACY=LOW RESULT=SAME (final reconciliation agrees; DECISION: both 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:N/I:N/A:H';*CWE-835;*CWE-20;**CWE-400;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'Corrupt CPER ring metadata can yield an entry size below one dword or a masked pointer increment of zero, so overflow recovery repeatedly examines the same entry while holding the CPER ring mutex. This is a logic and availability bug with no demonstrated invalid memory access, information leak, UAF, OOB access, or arbitrary write primitive. For the CVSS the PR:L value reflects that a local GPU workload or delegated GPU user context is the highest still defensible attacker model, although reliable control of malformed CPER contents is not established. The supported impact is a stalled CPER writer and blocked CPER ring users, with paranoid availability impact covering possible loss of the GPU RAS reporting path rather than a proven host wide kernel crash. Automated impact decision path. The original SimpleNet classifier selected MODERATE. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE to LOW because the CVSS score, vector or bug class threshold rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was LOW. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	MAYBE	INIT HARDWARE TEST  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

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

2. Signal breakdown

* +1 Availability impact: a corrupt entry size can produce no read-pointer progress, causing overflow recovery to spin while holding `ring_lock` and stalling the CPER writer/ring users.
* No reliable kernel-crash point: the commit supports a worker/ring-path hang, not panic or host-wide fatal failure.
* No corruption point: the patch shows no heap OOB write, UAF, invalid dereference, or write outside the ring’s intended metadata.
* B5-R does not apply: although recovery repeatedly examines one entry, prerequisite (1), a confirmed retry-accumulated heap/slab OOB write, is absent. Later consumption of OOB-corrupted structured state is also not shown.
* No remote, local-unprivileged, authorization, confidentiality, integrity, or strong exploit-leverage bonus is supported.

3. Reachability analysis

The malformed CPER contents originate in the AMD GPU RAS reporting path, but the supplied evidence does not establish that a normal local GPU client can deliberately create the corrupt entry or reliably invoke the overflow condition. The complete privilege boundary is therefore unknown; local render-node access, namespace-scoped capability, host UID 0, and host-admin requirements are not proven. No special timing penalty is applied merely because overflow/recovery conditions are needed. AMD GPU/RAS support is a hardware prerequisite, but the evidence does not establish rare physical hardware or attacker-controlled device input warranting a penalty.

4. Primitive and severity reading

The exact defect is a zero-progress ring-pointer update causing an infinite recovery loop under a mutex. It is Class C availability/invalid-state behavior, not an active-object corruption primitive. The fix detects unchanged `rptr`, empties the ring, and exits. Shown impact is loss or blockage of the CPER reporting path; host panic, host-wide DoS, memory corruption, and attacker control over malformed CPER metadata remain unproven. Important-candidate retention is unwarranted, and automatic downgrade is allowed.

5. One-sentence report phrase

Corrupt AMDGPU CPER entry sizing can stall ring overflow recovery under its mutex, but no memory-corruption or host-wide crash primitive is demonstrated.

6. Manual review advice

NO MANUAL CHECK NEEDED

The patch supports a constrained availability bug, while B5-R and authorization-preservation prerequisites are absent.

7. Call-site confidence

Call-site confidence: high

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

Patch: drm/amd/ras: reset CPER ring on corrupt entry size [ Upstream
Commit: a98d0d49757a113ce17960262b9cd4ccc1420108
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a98d0d49757a113ce17960262b9cd4ccc1420108

Changed files:
  drivers/gpu/drm/amd/amdgpu/amdgpu_cper.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=a98d0d49757a113ce17960262b9cd4ccc1420108

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

The original Linux kernel CVE announcement for CVE-2026-98894 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98894

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:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.7

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: unknown
  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).