[CVE-2026-68109][LOW] drm/amdgpu/sdma7.1: replace BUG_ON() with WARN_ON()

[CVE-2026-68109][LOW] drm/amdgpu/sdma7.1: replace BUG_ON() with WARN_ON()

[AL-KERNEL]

CVE: CVE-2026-68109
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amdgpu/sdma7.1: replace BUG_ON() with WARN_ON()
Commit: 253b1401862b9eb2be54f63546505a40a14672dd
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=253b1401862b9eb2be54f63546505a40a14672dd
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68109
Analysis date: Mon, 10 Aug 2026 12:52:36 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
AMDGPU SDMA 7.1 used BUG_ON for an unaligned internal fence address, allowing an avoidable local kernel panic if the driver invariant is violated, but no memory corruption or privilege escalation primitive is shown.

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

The original Linux kernel CVE announcement for CVE-2026-68109 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68109

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-2026-68109	LOW	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-617;CWE-703;**CWE-400;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'amdgpu SDMA 7.1 fence emission used BUG_ON when the fence address was not 4 byte aligned. If this internal invariant is violated, the kernel panics instead of reporting a recoverable driver warning. For the CVSS the PR:L is used for the paranoid score because a local user with access to the DRM render or card device may be able to exercise GPU submission paths, but the fence address itself appears to be driver allocated and not directly attacker controlled. The issue is not network reachable. Impact is denial of service via kernel crash only. No memory corruption, information disclosure, or privilege escalation primitive is indicated by this patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)  SKIP CVE-2026-68109 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	WARNONLY SIMPLEFIX HARDWARE 	-	-	checked

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

ActionableScore=1
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Paranoid signals:

* Local unprivileged trigger: +1. A local user with access to DRM render or card devices may be able to exercise GPU submission paths that eventually emit SDMA fences.
* Reliable kernel crash / strong DoS: +1. The old BUG_ON could panic the kernel if the fence address alignment invariant is violated.
* Hard or unreliable condition: -1. The addr value appears to be driver managed and the patch does not show direct attacker control over an unaligned fence address.
* Physical-only or hardware-specific condition: -1. The issue is specific to AMDGPU SDMA 7.1 hardware and driver paths.

Not applied:

* Generic memory corruption: +0. No UAF, OOB write, double free, overwrite, refcount issue, or stale object reuse is shown.
* Privilege escalation plausible: +0. No corruption primitive or privilege boundary bypass is indicated.
* Confidentiality / integrity impact: +0. The impact is limited to crash behavior from BUG_ON.
* High-control device API bonus: +0. DRM access alone is not enough without evidence of userspace control over memory layout, object lifetime, DMA mappings, or fence address selection.

Call-site confidence: medium. The changed function is visible, but the full callers and provenance of addr are not included.

## 3. Reachability analysis

The most plausible trigger is local, through AMDGPU command submission or driver activity that reaches sdma_v7_1_ring_emit_fence(). In typical desktop or GPU compute deployments, access to DRM render nodes may be available to non-root local users, so PR:L is defensible for a paranoid interpretation. However, the actual fence address appears to be allocated or selected by the driver, not directly supplied by userspace, so reliable triggering is uncertain.

The issue is not network reachable. Containers only matter if GPU device nodes are passed through to the container. The affected path is hardware and driver specific, not a broad default kernel path.

## 4. Severity interpretation

This behaves like a low-end DoS robustness issue rather than an Important-class vulnerability. The patch replaces BUG_ON with WARN_ON, indicating that the problematic condition should not crash the whole kernel. There is no evidence of memory corruption, privilege escalation, data disclosure, or persistent integrity impact. The theoretical risk is a local kernel panic if the invariant can be reached, but realistic attacker control is weak.

## 5. One-sentence report phrase

AMDGPU SDMA 7.1 used BUG_ON for an unaligned internal fence address, allowing an avoidable local kernel panic if the driver invariant is violated, but no memory corruption or privilege escalation primitive is shown.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed or handled as low-priority unless later evidence shows that unprivileged users can reliably force an unaligned fence address through a GPU submission path.

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

Patch: drm/amdgpu/sdma7.1: replace BUG_ON() with WARN_ON()
Commit: 253b1401862b9eb2be54f63546505a40a14672dd
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=253b1401862b9eb2be54f63546505a40a14672dd

Commit description:

There's no need to crash the kernel for these cases.

Reviewed-by: Vitaly Prosyak <vitaly.prosyak@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit c4f230b )
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/amd/amdgpu/sdma_v7_1.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=253b1401862b9eb2be54f63546505a40a14672dd

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

The original Linux kernel CVE announcement for CVE-2026-68109 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68109

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: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: 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).