[CVE-2026-99001][IMPORTANT] drm/xe/i2c: cancel the client work on remove [ Upstream

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-99001
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: NO
Patch: drm/xe/i2c: cancel the client work on remove [ Upstream
Commit: 2efa187fd4c9b8d7edcae0c1acf46739ce39fd01
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2efa187fd4c9b8d7edcae0c1acf46739ce39fd01
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99001
Analysis date: Mon, 26 Oct 2026 14:36:16 -0400
ActionableScore: 4
ActionableScore lower bound: unknown
Actionable bucket: Borderline / manual review recommended
Manual review required: YES

Summary:
Xe I2C removal can race queued client work, causing stale adapter use and a fixed-offset client-pointer write through a freed devm work context.

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

The original Linux kernel CVE announcement for CVE-2026-99001 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99001

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: IMPORTANT
Manual review required: YES

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
======================================================================

CVE-2026-99001	IMPORTANT	https://www.kernelcve.org/list/?q=CVE-2026-99001 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT IMPORTANT AEGIS_AS=6 LEGACY=IMPORTANT RESULT=SAME INDEPENDENT_LEGACY=MODERATE_KPANIC INDEPENDENT_RESULT=DIFF TEMP_KPANIC_MERGE=IMPORTANT_WINS_DISAGREEMENT PRE_MERGE_LEGACY=MODERATE_KPANIC (final reconciliation agrees; DECISION: both IMPORTANT)	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-416;CWE-362;*CWE-672;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A race in xe_i2c_remove can leave xe_i2c_client_work queued or running while the I2C adapter and the devm allocated struct xe_i2c are being released. The callback can dereference a freed adapter in i2c_new_client_device and can write the new client pointer through freed xe_i2c memory, providing a concrete UAF access and potential memory corruption primitive rather than a warning only. For the CVSS the PR:H base value reflects that reliable device unbind, driver removal, or equivalent Xe teardown normally requires administrative control. For the CVSS the PR:L paranoid value covers deployments that delegate device lifecycle operations to a container or service account. AC:H reflects the required workqueue and teardown timing window. Impact is at least a local denial of service via kernel crash and in the worst defensible case may allow privilege escalation through kernel memory corruption. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 7 and the production ActionableScore returned 4 with recommendation Borderline / manual review recommended. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were final reconciliation stage MODERATE_KPANIC to IMPORTANT because KP specialist did not establish a qualifying panic. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were TEMP_KPANIC_MERGE_IMPORTANT_WINS and KPANIC_UNSUPPORTED_REMOVED. The independent weaker Aegis shadow evaluated CVSS 0.8 and ActionableScore 6 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was IMPORTANT. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is IMPORTANT.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 4)	MAYBE	USB INIT UAF HARDWARE TEMP_KPANIC_MERGE_IMPORTANT_WINS KPANIC_UNSUPPORTED_REMOVED	-	-	checked

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

ActionableScore=4
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 4.
* Conservative score: 4; no floor or cap applied.
* Raw paranoid score: 4.
* Paranoid score: 4; no separate controlled-reuse or post-free-state primitive supports another point.
* Final recommended bucket: **Borderline / manual review recommended**::

2. Signal breakdown

* +2 — Real UAF/lifetime violation: queued work can execute after the adapter is released or after the devm-allocated `struct xe_i2c` is freed.
* +1 — Constrained post-free overwrite: the callback can store a newly created client pointer into `i2c->client[]` through freed `xe_i2c` storage. The offset and kernel-derived payload are fixed; target selection is not shown.
* +1 — Plausible kernel crash/strong DoS from stale adapter dereference or callback execution through freed context.
* No race penalty: a teardown/workqueue ordering is required, but the supplied evidence does not establish a genuinely narrow or uncontrollable timing window.
* No structured-stale leverage: attacker-controlled reclaim, replacement contents, callbacks from reclaimed data, or directed target selection are not shown.
* No extra availability, confidentiality, integrity, arbitrary-write, or LPE points.
* NEW52/B5-R does not apply: there is no retry-accumulated heap OOB write.
* No repeated release/refcount mutation is shown; FLOOR 5 does not apply.

3. Reachability analysis

The vulnerable sequence requires Xe I2C teardown while notifier-scheduled work remains queued or running. Normal device unbind/removal commonly involves administrative device-lifecycle control, but the supplied patch does not prove the complete trigger is restricted to effective host administration or available through delegated/container privileges. Therefore both host-admin and namespace scope remain unknown. No ordinary render-node ioctl trigger, attacker-controlled retry loop, special sysctl, or externally controllable hot-unplug path is established.

4. Primitive and severity reading

This is a real asynchronous teardown UAF involving fixed stale objects: a released DesignWare adapter and a devm-freed `xe_i2c` work context. It is stronger than a warning-only race because a pointer store through freed storage is explicitly described. However, the stale operation is teardown-bound, and neither controlled reclaim nor attacker-shaped post-free state is shown. It therefore remains constrained CLASS_B rather than CLASS_A.

The shown impact is kernel memory misuse and plausible crash. Exploitation through reuse of the freed allocation is theoretical. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` reflect the fixed, low-control asynchronous context, while manual review remains appropriate because the callback performs a concrete post-free write.

5. One-sentence report phrase

Xe I2C removal can race queued client work, causing stale adapter use and a fixed-offset client-pointer write through a freed devm work context.

6. Manual review advice

MANUAL CHECK RECOMMENDED

Confirm the actual permissions and repeatability of Xe device teardown and whether slab reuse can occur before the stale pointer store.

7. Call-site confidence

Call-site confidence: high

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

Patch: drm/xe/i2c: cancel the client work on remove [ Upstream
Commit: 2efa187fd4c9b8d7edcae0c1acf46739ce39fd01
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2efa187fd4c9b8d7edcae0c1acf46739ce39fd01

Changed files:
  drivers/gpu/drm/xe/xe_i2c.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=2efa187fd4c9b8d7edcae0c1acf46739ce39fd01

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

The original Linux kernel CVE announcement for CVE-2026-99001 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99001

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: 4

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: IMPORTANT
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): IMPORTANT

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).