[CVE-2026-68252][LOW] drm/amdgpu/sdma7.0: replace BUG_ON() with WARN_ON()

[CVE-2026-68252][LOW] drm/amdgpu/sdma7.0: replace BUG_ON() with WARN_ON()

[AL-KERNEL]

CVE: CVE-2026-68252
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amdgpu/sdma7.0: replace BUG_ON() with WARN_ON()
Commit: 395bf099ef7153227600a2d8cb087f45c4a277b6
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=395bf099ef7153227600a2d8cb087f45c4a277b6
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68252
Analysis date: Mon, 10 Aug 2026 14:28:00 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
AMDGPU SDMA 7.0 used `BUG_ON()` for a misaligned fence address check, allowing a local GPU path to panic the kernel if the internal invariant is violated, with no evidence of memory corruption or privilege escalation.

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

The original Linux kernel CVE announcement for CVE-2026-68252 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68252

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-2026-68252	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-703;CWE-754;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'amdgpu SDMA 7.0 used BUG_ON when emitting a fence if the fence address was not aligned to a 4 byte boundary. If this internal invariant was violated, the host kernel could panic instead of only reporting the bad condition. For the CVSS the PR:L is used for the higher score because unprivileged local users may have access to DRM render nodes and can submit GPU workloads, even though the exact misaligned fence address is normally driver controlled. The issue is not network reachable and requires local interaction with the GPU driver path. Impact is denial of service via kernel crash only. No credible memory corruption, information disclosure, or privilege escalation primitive is indicated by this patch.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)  SKIP CVE-2026-68252 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

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

ActionableScore=2
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: **1**
* Paranoid score: **2**
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Conservative signals:

* Reliable kernel crash / strong DoS: **+1**. The original code used `BUG_ON(addr & 0x3)`, so if the misaligned fence address condition is reached, the kernel can panic.
* Hard or unreliable trigger / special condition: **-1**. The fence address appears to be an internal driver value, not clearly attacker-controlled from the patch.
* Availability impact realistic: **+1**. A triggered `BUG_ON()` is host-wide availability impact.

Conservative total: **1**

Paranoid additional signal:

* Local unprivileged trigger: **+1**. Local users may have access to DRM render nodes and may be able to exercise GPU submission paths, although direct control over the misaligned fence address is not shown.

Paranoid total: **2**

Not counted:

* No generic memory corruption. The patch only replaces `BUG_ON()` with `WARN_ON()`.
* No UAF, OOB write, double free, type confusion, refcount misuse, or arbitrary write primitive is shown.
* No confidentiality or integrity impact is supported.
* No privilege escalation path is indicated.
* No network reachability.

## 3. Reachability analysis

The affected path is in the AMDGPU SDMA 7.0 fence emission code. A local user may be able to reach GPU submission paths through DRM render nodes, but the checked `addr` value is normally produced by the kernel driver rather than directly supplied by userspace. This makes reliable triggering uncertain.

Namespaces or containers may matter only if GPU device nodes are delegated into the container. Without access to the AMDGPU device node, the bug is not reachable. The path is hardware-dependent and applies only to systems using affected AMDGPU SDMA 7.0 hardware and driver support.

Call-site confidence: **medium**. The changed function is visible, but the full caller chain and user control over `addr` are not provided.

## 4. Severity interpretation

This behaves like an ordinary local DoS issue, not an Important-class vulnerability. The realistic impact is kernel panic if an internal alignment invariant is violated. The theoretical concern is limited to availability because the patch does not show memory corruption, stale object lifetime, attacker-controlled overwrite, information disclosure, or privilege escalation.

## 5. One-sentence report phrase

AMDGPU SDMA 7.0 used `BUG_ON()` for a misaligned fence address check, allowing a local GPU path to panic the kernel if the internal invariant is violated, with no evidence of memory corruption or privilege escalation.

## 6. Manual review recommendation

**NO MANUAL CHECK NEEDED**

This can be handled as low-priority Moderate or Low-like triage unless additional evidence shows that unprivileged users can reliably force the misaligned fence address or that the warning masks a deeper corruption path.

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

Patch: drm/amdgpu/sdma7.0: replace BUG_ON() with WARN_ON()
Commit: 395bf099ef7153227600a2d8cb087f45c4a277b6
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=395bf099ef7153227600a2d8cb087f45c4a277b6

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 9723a8b )
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/amd/amdgpu/sdma_v7_0.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=395bf099ef7153227600a2d8cb087f45c4a277b6

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

The original Linux kernel CVE announcement for CVE-2026-68252 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68252

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: 1
  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).