[CVE-2026-68110][LOW] drm/amdgpu/sdma4.4.2: replace BUG_ON() with WARN_ON()

[CVE-2026-68110][LOW] drm/amdgpu/sdma4.4.2: replace BUG_ON() with WARN_ON()

[AL-KERNEL]

CVE: CVE-2026-68110
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amdgpu/sdma4.4.2: replace BUG_ON() with WARN_ON()
Commit: 256d6f4803a93df96579c1ffdcb56518b9304f76
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=256d6f4803a93df96579c1ffdcb56518b9304f76
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68110
Analysis date: Mon, 10 Aug 2026 17:50:03 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A reachable BUG_ON() in the AMDGPU SDMA 4.4.2 fence emission path could allow a local user with GPU device access to crash the kernel if an unaligned internal fence address is reached, with no evidence of confidentiality impact, integrity impact, or privilege escalation.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-68110 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68110

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-68110	LOW	CHECK WITH IMPACT FROM ORIG NN LOW	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-617;CWE-754;CWE-703;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'A reachable BUG_ON() in the AMDGPU SDMA 4.4.2 fence emission path can crash the kernel if the fence address is not 4 byte aligned. The affected value appears to be driver internal state rather than direct user controlled packet data, so reliable triggering is likely configuration and state dependent. For the CVSS the PR:L is used because a local user with access to the DRM render device may be able to exercise GPU submission or reset paths that reach fence emission, but full administrative privileges are not necessarily required in common desktop or compute deployments. The issue is not network reachable. Impact is denial of service via kernel crash only, with no evidence of confidentiality or integrity impact or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)  SKIP CVE-2026-68110 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	WARNONLY SIMPLEFIX HARDWARE  INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. A local user with access to the AMDGPU DRM render device may be able to exercise GPU submission or reset paths that reach SDMA fence emission.
* Reliable kernel crash / strong DoS: +1. The old code used BUG_ON() on an unaligned fence address, which can intentionally crash the kernel if reached.
* Hard or unreliable trigger: -1. The checked address appears to be driver internal state, not direct user supplied input, so reliable triggering is likely state dependent.
* Broad/default/common subsystem exposure: +1. AMDGPU DRM render device access is common on systems with affected AMD GPUs.

Paranoid difference:

* Paranoid score removes the hard trigger penalty if local GPU workloads can naturally reach the bad fence state in a given deployment, resulting in score 3.

No memory corruption signals are awarded. The patch does not show UAF, OOB access, double free, stale callback, refcount abuse, arbitrary write, page-cache corruption, or ownership bypass.

## 3. Reachability analysis

The issue is local only and is not network reachable. The most plausible trigger is a local process with access to AMDGPU DRM interfaces, commonly via a render node on desktop or GPU compute systems. Full root privileges are not clearly required, but the attacker must be able to use the affected GPU device. Containers may matter only if DRM device nodes are passed through to the container. The affected path is hardware and driver specific, and the bad condition depends on an internal fence address becoming unaligned.

Call-site confidence: medium. The changed function is visible, but the patch does not include full caller context showing how an attacker can force the bad address.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like local DoS issue, not an Important-class vulnerability. The realistic impact is kernel crash through a reachable assertion. Theoretical escalation is not supported by the patch because replacing BUG_ON() with WARN_ON() does not indicate a concrete memory corruption primitive or attacker-controlled overwrite.

## 5. One-sentence report phrase

A reachable BUG_ON() in the AMDGPU SDMA 4.4.2 fence emission path could allow a local user with GPU device access to crash the kernel if an unaligned internal fence address is reached, with no evidence of confidentiality impact, integrity impact, or privilege escalation.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed for general security triage because it is a DoS-only assertion removal with no demonstrated memory corruption, no network exposure, and no supported LPE primitive. Manual review is only useful if local GPU-triggered host crashes are in scope for the affected product.

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

Patch: drm/amdgpu/sdma4.4.2: replace BUG_ON() with WARN_ON()
Commit: 256d6f4803a93df96579c1ffdcb56518b9304f76
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=256d6f4803a93df96579c1ffdcb56518b9304f76

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 fa4f86a )
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/amd/amdgpu/sdma_v4_4_2.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=256d6f4803a93df96579c1ffdcb56518b9304f76

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

The original Linux kernel CVE announcement for CVE-2026-68110 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68110

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:H
  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: unknown
  Paranoid ActionableScore: 2

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).