[CVE-2026-93068][LOW] drm/amd/display: Fix DM I2C teardown race [ Upstream

[CVE-2026-93068][LOW] drm/amd/display: Fix DM I2C teardown race [ Upstream

[AL-KERNEL]

CVE: CVE-2026-93068
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amd/display: Fix DM I2C teardown race [ Upstream
Commit: 8ee385305e8902fa6fbfd66b5a112238292567b6
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8ee385305e8902fa6fbfd66b5a112238292567b6
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93068
Analysis date: Thu, 17 Sep 2026 23:11:02 -0400
ActionableScore: 1
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-2026-93068 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93068

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-2026-93068	LOW	https://www.kernelcve.org/list/?q=CVE-2026-93068 CHECK WITH IMPACT FROM ORIG NN MODERATE	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-362;**CWE-476;*CWE-664;BEST CVSS score: '4.7';DESCR 'A race exists between AMD Display Manager teardown and I2C transfers through i2c-dev. An I2C adapter can remain accessible while the backing display state is already being destroyed, and a concurrent transfer can enter amdgpu_dm_i2c_xfer and trigger a NULL pointer dereference that crashes the kernel. For the CVSS the PR:L is used because an attacker needs local access to an exposed I2C device node, normally granted through device permissions or membership in an I2C related group. The race also requires a device removal or teardown event, therefore AC:H is appropriate. The issue is not network reachable. Impact is local denial of service through a kernel crash. No use after free or other memory corruption primitive is demonstrated by the patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)  SKIP CVE-2026-93068 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	DANGER NULLPTR NOMEMCHK RACE HARDWARE  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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

ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::

No floor or cap was applied. Conservative and paranoid scores are identical because the patch establishes a NULL pointer dereference and kernel crash, but does not establish a UAF, post-free reuse, refcount mutation, controlled memory corruption, or security-boundary bypass.

2. Signal breakdown

* +1 Reliable kernel crash / strong DoS. The supplied trace shows a NULL pointer dereference in `amdgpu_dm_i2c_xfer()` reached through `i2cdev_ioctl_rdwr()` and `i2c_transfer()`.

Important non-awarded signals:

* +0 Real UAF. The patch and commit describe teardown ordering and a NULL pointer dereference. They do not establish that an object is freed and later dereferenced as attacker-useful reclaimed storage.
* +0 Memory corruption primitive. No OOB access, arbitrary write, type confusion, controlled reclaim, callback dispatch, or refcount corruption is shown.
* +0 Local unprivileged trigger. Access to `/dev/i2c-*` may be granted to an `i2c` group or another delegated account, but the complete trigger also requires concurrent AMD display teardown or device removal. Below-host-admin reachability for the complete sequence is not established.
* +0 Remote reachability. The vulnerable path is reached through local `i2c-dev` ioctl handling and is not network reachable.
* +0 Attacker-influenced active-object lifetime manipulation. The patch does not show attacker control over DM state allocation, replacement, reuse, or teardown sequencing.
* +0 Structured stale-object leverage. The demonstrated stale path is an immediate NULL dereference, not meaningful consumption of attacker-controlled structured fields after reuse.
* +0 Confidentiality and integrity impact. No disclosure or unauthorized modification primitive is demonstrated.
* +0 Additional Availability impact. The observed kernel crash is already counted by the Reliable kernel crash signal.
* -0 Hard race penalty. The issue is a teardown race, but supplied evidence does not prove that the timing is exceptionally narrow, one-shot, or materially difficult to repeat.

3. Reachability analysis

The immediate caller is the userspace `i2c-dev` interface through `i2cdev_ioctl_rdwr()`. An attacker would need access to the relevant exposed AMD DM I2C adapter device node, normally `/dev/i2c-*`, and would need an I2C transfer to overlap with AMD display-manager teardown.

The supplied evidence does not establish who can cause the teardown. Device removal may result from hot unplug, driver unbind, PCI removal, reset, suspend-related paths, or administrative operations, but the exact trigger path is not provided. Therefore, host-admin privilege is not proven as required, but below-host-admin completion of the entire trigger sequence is also not proven.

For DRM and display environments, an ordinary logged-in user, compositor, DRM master, display server, delegated graphics service, and host administrator have different privileges. The supplied patch does not show that an ordinary user or DRM master can independently initiate the required `dm_hw_fini()` teardown while retaining I2C adapter access. Namespace-scoped privilege is not established. No network namespace or container path is involved.

The bug affects AMDGPU display-manager I2C adapters. Common AMD GPU hardware is not rare hardware, but the vulnerable path requires an exposed DM I2C adapter and a concurrent device teardown event.

4. Primitive and severity interpretation

The exact primitive is a teardown ordering race that leaves an AMD Display Manager I2C adapter visible to userspace after backing DM state has begun teardown. A concurrent I2C transfer can enter `amdgpu_dm_i2c_xfer()` and dereference a NULL pointer.

This is not established as a real UAF. The patch prevents access by unregistering and releasing the I2C adapters before HPD, IRQ, and DM state teardown, and waits for in-flight adapter users to drain. That ordering fix protects the state lifetime, but the demonstrated pre-fix consequence is specifically a NULL pointer dereference rather than reuse of freed memory.

The affected state is driver/display-management state, but the supplied evidence shows only shallow crash behavior. There is no concrete repeated release, put, free, or refcount mutation through a dangling reference. There is no controlled replacement, attacker-shaped post-free state, callback influence, arbitrary read/write, information disclosure, integrity violation, or privilege escalation path.

PrimitiveClass is CLASS_C because the demonstrated behavior is crash-only invalid-state behavior. ImportantCandidate is NO because meaningful exploitation leverage beyond the kernel crash is not unresolved in the supplied evidence. AutoDowngradeAllowed is YES because this is a constrained local driver teardown crash without a demonstrated corruption or boundary-bypass primitive.

Likely operational severity is local denial of service when an authorized I2C-device user overlaps a transfer with AMDGPU DM teardown.

5. One-sentence report phrase

A race between AMD Display Manager teardown and i2c-dev transfers can leave an I2C adapter accessible after its backing state is torn down, causing a local NULL pointer dereference and kernel crash.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch establishes a local NULL pointer dereference during driver teardown, with no demonstrated UAF, memory corruption, privilege escalation, information disclosure, or network reachability.

7. Call-site confidence

Call-site confidence: medium

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

Patch: drm/amd/display: Fix DM I2C teardown race [ Upstream
Commit: 8ee385305e8902fa6fbfd66b5a112238292567b6
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8ee385305e8902fa6fbfd66b5a112238292567b6

Changed files:
  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

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=8ee385305e8902fa6fbfd66b5a112238292567b6

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

The original Linux kernel CVE announcement for CVE-2026-93068 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93068

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: Not available
  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: unknown
  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).