[CVE-2026-93244][LOW] drm/sysfb: simpledrm: Improve stride validation

[CVE-2026-93244][LOW] drm/sysfb: simpledrm: Improve stride validation

[AL-KERNEL]

CVE: CVE-2026-93244
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/sysfb: simpledrm: Improve stride validation
Commit: 6892f0a2f6b5990b9572ba043dd14dd4df6bb3f0
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6892f0a2f6b5990b9572ba043dd14dd4df6bb3f0
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93244
Analysis date: Thu, 24 Sep 2026 12:40:04 -0400
ActionableScore: 0
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-2026-93244 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93244

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-2026-93244	LOW	https://www.kernelcve.org/list/?q=CVE-2026-93244 CHECK WITH IMPACT FROM ORIG NN MODERATE	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:L';CWE-190;CWE-681;*CWE-20;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '3.3';DESCR 'An integer range validation issue exists in simpledrm framebuffer stride handling. drm_format_info_min_pitch can return a value larger than INT_MAX, while the resulting value is later used as a framebuffer stride. A malformed or unusually large firmware framebuffer geometry can therefore result in an invalid stride and failure of simpledrm initialization or incorrect display handling. The patch context does not demonstrate an out of bounds access, use after free, information leak, arbitrary write, or privilege escalation primitive. For the CVSS the PR:L rating in the paranoid score reflects environments where a reduced capability user can control virtual machine display configuration, firmware supplied framebuffer parameters, or related boot configuration. The issue is not directly network reachable. Impact is expected to be limited availability degradation of framebuffer or display initialization.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	YES	SIMPLEFIX HARDWARE LINUS  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS	NO	NO	checked

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

ActionableScore=0
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 0
* Paranoid score: 0
* Final recommended bucket: **Ordinary Moderate**::

The patch is a validation-only fix. No concrete corruption, lifetime, authorization, disclosure, or privilege-escalation primitive is established.

2. Signal breakdown

* +0 No concrete security primitive. The change rejects a computed pitch greater than INT_MAX before assigning it to stride.
* +0 No UAF, stale pointer, refcount issue, OOB access, arbitrary write, or controlled object corruption is established.
* +0 No reliable kernel crash or host-wide DoS is demonstrated. The visible result of the new check is failure to create the simpledrm device.
* +0 Remote reachability is not established. The relevant framebuffer geometry originates from firmware or boot-time sysfb state, not from a network-facing interface.
* +0 Local unprivileged trigger is not established. The patch does not show an ordinary user controlling early simpledrm framebuffer geometry.
* +0 Confidentiality and integrity impact are not awarded. There is no disclosure path, protected-state modification, or memory-access primitive.
* +0 Strong or weak LPE leverage is not awarded. Integer range validation alone does not establish privilege escalation.
* +0 No race or timing penalty applies. The issue is not a race.
* +0 No rare-hardware penalty applies. The code is display-related, but the patch does not establish a physical-only or uncommon-hardware prerequisite.

3. Reachability analysis

The affected code runs during simpledrm device creation using sysfb framebuffer parameters. The supplied patch does not establish that a normal logged-in user, DRM client, DRM master, compositor, or display server can control the width, pixel format, or firmware framebuffer geometry that reaches this path.

A host administrator may be able to influence bootloader, firmware, virtual-machine display, or boot-time framebuffer configuration in some deployments. However, the complete privilege boundary is not shown, so HostAdminRequired is UNKNOWN rather than YES.

Namespace-scoped reachability is not established. No network namespace, user namespace, delegated DRM permission, or complete below-host-admin trigger sequence is visible. The issue is not network reachable and does not require a race.

4. Primitive and severity interpretation

The exact issue is an unchecked conversion or range mismatch. drm_format_info_min_pitch returns a u64 pitch, while simpledrm requires the computed stride to remain within INT_MAX. The patch rejects oversized values before assigning the pitch to stride.

This is not an active structured-object lifetime defect, fixed stale storage issue, UAF, double release, refcount mutation, ownership violation, or security-boundary bypass. The supplied context does not demonstrate that an oversized pitch reaches an OOB access, causes an invalid allocation or copy length, corrupts memory, leaks data, or modifies protected kernel state.

The practical consequence supported by the patch is limited to rejection of invalid framebuffer geometry or failure of simpledrm initialization. ImportantCandidate is NO because no unresolved Important-class primitive is established. AutoDowngradeAllowed is YES because there is no demonstrated corruption or authorization primitive that would be lost by automated low-priority handling.

5. One-sentence report phrase

An integer range validation issue in simpledrm could allow an oversized computed framebuffer pitch to be used as a stride, potentially causing simpledrm initialization failure or incorrect display handling without a demonstrated memory-corruption or privilege-escalation primitive.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch is a narrow validation improvement and the supplied evidence establishes no concrete security-relevant primitive beyond invalid framebuffer configuration handling.

7. Call-site confidence

Call-site confidence: medium

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

Patch: drm/sysfb: simpledrm: Improve stride validation
Commit: 6892f0a2f6b5990b9572ba043dd14dd4df6bb3f0
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6892f0a2f6b5990b9572ba043dd14dd4df6bb3f0

Commit description:

Validate the computed stride against the maximum value INT_MAX.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Fixes: 7bfa5c7 ("drm/simpledrm: Compute linestride with drm_format_info_min_pitch()")
Cc: <stable@vger.kernel.org> # v6.1+
Link: https://patch.msgid.link/20260625094509.157581-5-tzimmermann@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/sysfb/simpledrm.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=6892f0a2f6b5990b9572ba043dd14dd4df6bb3f0

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

The original Linux kernel CVE announcement for CVE-2026-93244 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93244

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:L/PR:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS score: 3.3

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: 0

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).