[CVE-2026-97493][MODERATE 7.0] drm/amdgpu: Bound GPIO I2C table entry count from VBIOS [ Upstream

[CVE-2026-97493][MODERATE 7.0] drm/amdgpu: Bound GPIO I2C table entry count from VBIOS [ Upstream

[AL-KERNEL]

CVE: CVE-2026-97493
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: drm/amdgpu: Bound GPIO I2C table entry count from VBIOS [ Upstream
Commit: f8f0985375c3b977757fd73e2b691ff1bf1ea7b9
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f8f0985375c3b977757fd73e2b691ff1bf1ea7b9
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97493
Analysis date: Thu, 24 Sep 2026 14:30:37 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
A malformed AMDGPU VBIOS GPIO I2C table can drive the parser beyond both the table and the fixed i2c_bus array, creating a firmware-mediated kernel OOB-write candidate that requires manual exploitation and reachability review.

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

The original Linux kernel CVE announcement for CVE-2026-97493 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97493

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: MODERATE 7.0
Manual review required: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-97493	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-97493 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:H/I:H/A:H';*CWE-787;CWE-125;CWE-191;*CWE-20;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'The AMDGPU ATOM BIOS parser derives the GPIO I2C entry count from a VBIOS supplied size without first rejecting an undersized header or limiting the result to the fixed i2c_bus array capacity. A corrupt or attacker controlled VBIOS can therefore cause excessive iteration, out of bounds reads from the BIOS image, and possible out of bounds writes while initializing I2C bus records. The immediate effect can be a kernel crash or system stall. Because an array overrun can corrupt adjacent kernel memory, confidentiality and integrity impact and potential privilege escalation cannot be excluded without analysis of the complete call paths and object layout. For the CVSS the PR:L in the paranoid score reflects environments where a reduced capability service, container root, or virtualization user can control a VBIOS image or device reinitialization without full host administration. The issue is not directly network reachable and normally requires local control of firmware data, an emulated GPU, or a device initialization path.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5)  SKIP CVE-2026-97493 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	HARDWARE  KPANIC INCREASED_TO_MODERATE7_FROM_LOW_BASED_ON_GUESSCVSS_AND_ACTIONABLESCOREHIGHER4	-	-	checked

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

ActionableScore=5
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

## 1. ActionableScore

* Raw conservative score: 5
* Conservative score: 5
* Raw paranoid score: 5
* Paranoid score: 5
* No floor or cap applied.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

## 2. Signal breakdown

Positive signals:

* +2 Strong corruption primitive. The commit explicitly states that the unchecked count can overrun the fixed `adev->i2c_bus[]` array. This establishes an OOB write candidate, not merely validation failure or an internal OOB read.
* +1 Firmware-mediated external influence. The count and records originate from VBIOS data, although direct remote reachability is not established.
* +1 Reliable kernel crash or strong DoS. An undersized size field can underflow the entry-count calculation, while an oversized field can cause extensive iteration and writes beyond the array.
* +1 Broad and realistically exercised path. The parser runs during ordinary AMDGPU device initialization on affected AMD GPU systems.

Important non-awarded signals:

* No additional OOB-read point. The OOB reads and array overrun arise from the same unchecked entry count.
* No Strong LPE bonus. Controlled target selection, useful adjacent-field corruption, and reliable privilege escalation are not demonstrated.
* No separate Confidentiality or Integrity bonus. The exact overwritten fields and any disclosure path are not visible.
* No Local unprivileged trigger point. Ordinary users, DRM clients, and compositors are not shown to control the VBIOS image used during device initialization.
* No direct remote-reachability point. Firmware or device mediation is required.
* No hardware penalty. AMD GPUs are not inherently rare, and the vulnerable initialization path is normal for affected devices.
* No privilege penalty. Host-admin-equivalent privilege is plausible for replacing physical VBIOS data, but it is not positively established for every environment, including virtual or emulated GPU configurations.
* No Real UAF, repeated release, refcount mutation, race, or lifetime floor applies.

## 3. Reachability analysis

The vulnerable input is a VBIOS-reported table size processed while AMDGPU initializes GPIO I2C records. A physical firmware image, firmware override, emulated GPU VBIOS, or another device-provisioning mechanism could supply malformed data.

The supplied evidence does not establish that an ordinary logged-in user, DRM master, compositor, display server, or delegated graphics service can replace this VBIOS or force initialization with attacker-selected contents. It also does not prove that host root is universally required. Therefore `HostAdminRequired=UNKNOWN`.

No user-namespace or network-namespace path is involved, so the complete operation is not namespace-scoped. No race is required. The principal prerequisite is initialization of an affected AMDGPU device with a malformed or attacker-controlled VBIOS table.

## 4. Primitive and severity interpretation

The exact primitive is an entry-count calculation based on an insufficiently validated 16-bit size:

* An undersized size can underflow the subtraction before division.
* An oversized or corrupt size can produce more entries than `AMDGPU_MAX_I2C_BUS`.
* The resulting loops can walk beyond the reported table and, in initialization paths, overrun the fixed `adev->i2c_bus[]` array.

This is not a UAF and does not involve stale storage. It is a firmware-derived OOB read and concrete OOB-write candidate against an active kernel device object.

The explicit fixed-array overrun supports `CLASS_A`. The demonstrated practical consequences are kernel memory corruption, excessive iteration, and likely crash or stall. Privilege escalation remains plausible only as an unresolved consequence of adjacent kernel-object corruption. No arbitrary write, controlled target, callback overwrite, credential corruption, or working LPE chain is established.

`ImportantCandidate=YES` because a concrete kernel OOB write must not be reduced to an ordinary validation bug without examining the loop bodies, destination layout, and attacker control over VBIOS records. `AutoDowngradeAllowed=NO` because automatic closure would discard an established corruption primitive with unresolved exploitation leverage.

## 5. One-sentence report phrase

A malformed AMDGPU VBIOS GPIO I2C table can drive the parser beyond both the table and the fixed i2c_bus array, creating a firmware-mediated kernel OOB-write candidate that requires manual exploitation and reachability review.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Review the complete loop bodies, `struct amdgpu_device` layout following `i2c_bus`, VBIOS record influence over written values, and whether virtual GPU or firmware-loading environments permit below-host-admin control of the parsed image.

## 7. Call-site confidence

Call-site confidence: medium

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

Patch: drm/amdgpu: Bound GPIO I2C table entry count from VBIOS [ Upstream
Commit: f8f0985375c3b977757fd73e2b691ff1bf1ea7b9
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f8f0985375c3b977757fd73e2b691ff1bf1ea7b9

Changed files:
  drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.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=f8f0985375c3b977757fd73e2b691ff1bf1ea7b9

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

The original Linux kernel CVE announcement for CVE-2026-97493 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97493

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:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 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: 5

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: MODERATE
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): MODERATE 7.0

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).