[CVE-2026-89812][LOW] drm/amdgpu: force complete the MES ring fences on reset

[CVE-2026-89812][LOW] drm/amdgpu: force complete the MES ring fences on reset

[AL-KERNEL]

CVE: CVE-2026-89812
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amdgpu: force complete the MES ring fences on reset
Commit: ebe7542553d008e2285e0fbba0c63f0295a7e694
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ebe7542553d008e2285e0fbba0c63f0295a7e694
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89812
Analysis date: Wed, 16 Sep 2026 10:23:12 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
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-2026-89812 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89812

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-2026-89812	LOW	https://www.kernelcve.org/list/?q=CVE-2026-89812 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:N/I:N/A:H';CWE-703;CWE-754;*CWE-664;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'AMDGPU MES scheduler fences are not force completed during an ASIC reset because MES rings do not use the DRM scheduler and are skipped by the normal completion loop. If MES has stopped responding timed out work can advance the software fence sequence beyond the value stored in writeback memory. The first MES submission after resume can then wait forever for a fence value that will never be written and a later reset can leave the GPU driver wedged. For the CVSS the PR:L rating reflects that an attacker needs local access to submit workloads through an accessible AMDGPU render or compute interface. Triggering the required MES timeout and reset condition is complex. The issue is not directly network reachable. Impact is denial of service affecting GPU operation and potentially host graphics or compute workloads.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)  SKIP CVE-2026-89812 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	INIT HARDWARE TEST PACKET 	-	-	checked

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

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

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Device availability impact. A MES timeout followed by reset can leave post-reset submissions waiting forever and can wedge GPU recovery after a later reset.
* No memory corruption signal. The patch addresses stale fence sequence state, not freed memory, an invalid pointer, OOB access, refcount misuse, or ownership corruption.
* No reliable host kernel crash signal. The reported result is failed GPU reset and wedged graphics or compute functionality, not a demonstrated kernel panic.
* No remote reachability signal. No network-controlled path is shown.
* No local unprivileged trigger signal. The supplied material does not establish that an ordinary user can reliably cause the MES timeout and complete reset sequence through an accessible render or compute interface.
* No strong or weak LPE leverage. No controlled reclaim, arbitrary write, callback control, disclosure, authorization bypass, or security-boundary bypass is established.
* No hardware rarity penalty. The issue is GPU-specific, but common AMDGPU hardware is not inherently rare or physical-only under the stated rules.
* No race penalty. This is an ordered stale fence-state recovery failure, not a demonstrated narrow timing race.

3. Reachability analysis

The affected path is reached during AMDGPU ASIC reset handling after MES has stopped responding. A complete trigger requires a supported AMDGPU device using MES scheduler rings, a condition that causes MES to time out, a GPU reset, and a post-reset MES submission.

The supplied patch does not show the userspace submission path, DRM permission checks, render-node policy, reset initiation conditions, or whether an ordinary logged-in user can reliably induce the required MES failure. Therefore below-host-admin reachability is not positively established, but host-admin-equivalent privilege is also not positively established.

No namespace-scoped capability path is involved in the supplied evidence. No prior host configuration, boot parameter, or special uncommon hardware requirement is demonstrated beyond a compatible AMD GPU with MES support.

4. Primitive and severity interpretation

The primitive is a stale synchronization-state mismatch between the MES software fence sequence and the hardware fence value retained in writeback GTT memory across a MODE1 reset. This is an invalid-state and recovery-handling failure, not a UAF, double free, stale post-lifetime dereference, refcount mutation, DMA ownership violation, or memory corruption primitive.

The demonstrated consequence is GPU recovery failure and potential GPU-driver wedge after reset. The patch does not establish host memory corruption, confidentiality impact, integrity impact, privilege escalation, or a meaningful security-boundary bypass. There is no active structured stale object use after free and no concrete repeated release or refcount operation.

PrimitiveClass is CLASS_C because the demonstrated behavior is primarily a device-level denial of service through invalid fence state. ImportantCandidate is NO because no unresolved Important-grade corruption or boundary primitive is present. AutoDowngradeAllowed is YES because the issue is a constrained GPU recovery availability failure without demonstrated exploitation leverage beyond the device wedge.

5. One-sentence report phrase

AMDGPU MES fence state can remain stale across a GPU reset and cause post-reset submissions to wait forever, resulting in GPU recovery failure and denial of service without demonstrated memory corruption or privilege escalation.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch establishes a fence synchronization and GPU recovery failure only. It does not establish a kernel corruption, lifetime, authorization, confidentiality, integrity, or privilege-escalation primitive.

7. Call-site confidence

Call-site confidence: medium

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

Patch: drm/amdgpu: force complete the MES ring fences on reset
Commit: ebe7542553d008e2285e0fbba0c63f0295a7e694
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ebe7542553d008e2285e0fbba0c63f0295a7e694

Commit description:

The MES scheduler ring has no drm scheduler (no_scheduler = true), so it is
skipped by the force-completion loop in amdgpu_device_pre_asic_reset(). It uses
a polling fence whose hw value lives in wb (GTT) memory and survives a MODE1
reset, while fence_drv.sync_seq keeps advancing for every packet.

When the reset is triggered because MES itself stopped responding, the
timed-out packets advance sync_seq past the last hw fence value MES wrote.
After resume the first MES submission polls forever on a seq that is never
written back, failing the resume and wedging the box on a second reset:

  amdgpu: MES ring buffer is full.
  amdgpu: *ERROR* ring gfx_0.0.0 test failed (-110)
  amdgpu: resume of IP block <gfx_v11_0> failed -110
  amdgpu: GPU reset end with ret = -110

Force complete the MES scheduler ring fences together with the scheduler rings
so their hw fence is realigned to sync_seq.

v2: cover all XCCs (one scheduler ring each), not just mes.ring[0].

Cc: stable@vger.kernel.org
Signed-off-by: Jesse Zhang <Jesse.Zhang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/amd/amdgpu/amdgpu_device.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=ebe7542553d008e2285e0fbba0c63f0295a7e694

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

The original Linux kernel CVE announcement for CVE-2026-89812 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89812

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).