[CVE-2026-99069][MODERATE REGULAR] Input: ati_remote2 - fix type confusion in device attribute handlers

[CVE-2026-99069][MODERATE REGULAR] Input: ati_remote2 - fix type confusion in device attribute handlers

[AL-KERNEL]

CVE: CVE-2026-99069
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: Input: ati_remote2 - fix type confusion in device attribute handlers
Commit: e44ec6b6d3c0b8ea089b589fa0cce49a4da66b89
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e44ec6b6d3c0b8ea089b589fa0cce49a4da66b89
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99069
Analysis date: Mon, 26 Oct 2026 22:53:01 -0400
ActionableScore: 3
ActionableScore lower bound: unknown
Actionable bucket: Borderline / manual review recommended
Manual review required: YES

Summary:
Local reads of affected ATI Remote 2 sysfs attributes can miscast a USB interface as a USB device and trigger an invalid kernel pointer dereference and system crash.

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

The original Linux kernel CVE announcement for CVE-2026-99069 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99069

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 REGULAR
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-2026-99069	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-99069 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE RESULT=DIFF (final Legacy and Aegis differ; FINAL: MODERATE, Aegis: MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H';CWE-843;CWE-704;CWE-822;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.1';DESCR 'A type confusion in ati_remote2 sysfs handlers treats a struct usb_interface device as a struct usb_device. The resulting invalid usb_device pointer is passed to usb_ifnum_to_if and can cause an invalid kernel pointer dereference when an affected channel_mask or mode_mask attribute is accessed. For the CVSS the PR:L value reflects that a local user can normally read these sysfs attributes and reach the show handlers. The demonstrated impact is local denial of service through a kernel oops or panic. Limited confidentiality impact is a grounded worst case because a show handler may format data reached through the invalid object chain, but reliable disclosure and an unprivileged write primitive are not established. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 6.1 and the production ActionableScore returned 3 with recommendation Borderline / manual review recommended. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage LOW to MODERATE_KPANIC because the manual review requirement was applied. ActionableScore thresholds stage MODERATE_KPANIC to MODERATE because the ActionableScore threshold rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK and DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 and V41_INHERITED_KPANIC_PROMOTION_BLOCKED and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 4.3 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3)	MAYBE	USB SIMPLEFIX HARDWARE LINUS  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 V41_INHERITED_KPANIC_PROMOTION_BLOCKED MANUAL_REVIEW_REQUIRED	-	-	checked

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

ActionableScore=3
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 3.
* Conservative score: 3; no floor or cap applied.
* Raw paranoid score: 3.
* Paranoid score: 3; unsupported disclosure or write effects are not scored.
* Final recommended bucket: **Borderline / manual review recommended**::

2. Signal breakdown

* +1 weak/indirect corruption candidate: `to_usb_device(dev)` performs an invalid container conversion on a `usb_interface` device, producing a bogus structured pointer subsequently consumed by `usb_ifnum_to_if()`.
* +1 reliable kernel crash/strong DoS: the invalid pointer chain plausibly causes an Oops or panic when the attribute is read.
* +1 local unprivileged trigger: supplied evidence grounds ordinary local read access to the affected sysfs show attributes.
* No hardware penalty: an attached supported USB device is required, but the evidence does not establish rare hardware or attacker-required physical access strongly enough for subtraction.
* No confidentiality point: formatting `ar2->channel_mask` or `mode_mask` does not establish reliable disclosure of unintended kernel bytes.
* No write primitive, controlled object replacement, UAF, OOB write, callback control, or LPE is shown.
* The store handlers do not prove an attacker-directed kernel write: the invalid chain may fault before obtaining usable `ar2` state.
* No separate availability point is awarded for the same crash.

3. Reachability analysis

The grounded path is a local user reading a sysfs attribute on a bound ATI Remote 2 USB interface; this does not require UID 0, a capability, or namespace-scoped privilege. The device and driver must already be present and bound, but no separate host-administrator action by the triggering user is shown. Store-handler permissions are not established, but they are unnecessary for the readable show-handler crash path. No race or retry sequence is involved.

4. Primitive and severity reading

The exact primitive is an invalid type conversion followed by structured dereferences through a bogus `usb_device` pointer. This is neither a lifetime violation nor controlled type confusion involving attacker-shaped replacement storage. Patch-supported impact is an invalid-pointer kernel fault; disclosure and useful writes remain speculative. Therefore this is CLASS_C, not B5-R, B3-PENDING, or an Important-preserving active-state corruption chain. ImportantCandidate is NO and auto-downgrade remains allowed because no material non-crash exploit primitive or trust-boundary uncertainty is demonstrated.

There is no authorization guard, DENY-to-ALLOW transition, protected resource, or B4 authorization-state issue.

5. One-sentence report phrase

Local reads of affected ATI Remote 2 sysfs attributes can miscast a USB interface as a USB device and trigger an invalid kernel pointer dereference and system crash.

6. Manual review advice

MANUAL CHECK RECOMMENDED

Confirm actual sysfs mode bits and whether any platform-specific behavior permits unintended data exposure or reaches a write before faulting.

7. Call-site confidence

Call-site confidence: high

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

Patch: Input: ati_remote2 - fix type confusion in device attribute handlers
Commit: e44ec6b6d3c0b8ea089b589fa0cce49a4da66b89
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e44ec6b6d3c0b8ea089b589fa0cce49a4da66b89

Commit description:

Previously, the channel_mask and mode_mask attributes were registered on
the parent usb_device via sysfs_create_group(). When commit b20d6bf
("Input: ati-remote2 - use driver core to instantiate device
attributes") converted the driver to let the driver core manage them via
dev_groups in struct usb_driver, the attributes moved to the bound
usb_interface devices, but the show and store callbacks were not updated
accordingly.

As a result, the callbacks still invoked to_usb_device() on a device
pointer belonging to a struct usb_interface, producing an invalid
usb_device pointer.

Use to_usb_interface() directly in the attribute handlers to obtain the
interface and its driver data.

Fixes: b20d6bf ("Input: ati-remote2 - use driver core to instantiate device attributes")
Assisted-by: DeepSeek-V4.1-Flash
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Link: https://patch.msgid.link/20261009040302.3087205-1-vulab@iscas.ac.cn
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/input/misc/ati_remote2.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=e44ec6b6d3c0b8ea089b589fa0cce49a4da66b89

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

The original Linux kernel CVE announcement for CVE-2026-99069 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99069

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: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:L/I:N/A:H
  The Best / paranoid CVSS score: 6.1

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: 3

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: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).