[CVE-2026-68087][LOW] HID: wacom: use GFP_ATOMIC in wacom_wac_queue_flush()

[CVE-2026-68087][LOW] HID: wacom: use GFP_ATOMIC in wacom_wac_queue_flush()

[AL-KERNEL]

CVE: CVE-2026-68087
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: HID: wacom: use GFP_ATOMIC in wacom_wac_queue_flush()
Commit: bbe1e55629bfaabd4b2e8125b48dd3503d74ac8b
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bbe1e55629bfaabd4b2e8125b48dd3503d74ac8b
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68087
Analysis date: Mon, 10 Aug 2026 15:05:50 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like. Borderline only under local HID injection assumptions
Manual review required: NO

Summary:
A sleepable GFP_KERNEL allocation in the Wacom HID raw_event path can execute from USB HID interrupt completion context, allowing a malicious device or local HID injection source to trigger a scheduling while atomic denial of service without evidence of memory corruption or privilege escalation.

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

The original Linux kernel CVE announcement for CVE-2026-68087 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68087

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.

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

CVE-2026-68087	LOW	CHECK WITH IMPACT FROM ORIG NN LOW	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:H';CWE-667;CWE-703;CWE-755;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'A sleepable GFP_KERNEL allocation in the Wacom HID raw_event path can run from USB HID interrupt completion context. A malicious or faulty HID device can drive this path and trigger a scheduling while atomic bug, causing a warning or kernel crash depending on kernel configuration. For the CVSS the PR:L is used in the paranoid score because a local process with access to a user HID injection interface or delegated HID device control may be able to trigger the same affected path. The issue is not network reachable and requires local device interaction or local HID injection capability. Impact is denial of service only. There is no supported evidence of UAF, OOB access, information disclosure, arbitrary write, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like. Borderline only under local HID injection assumptions (with actual score 2)	YES	USB SIMPLEFIX HARDWARE LINUS  INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	YES	NO	checked

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

ActionableScore=3
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 3
* Final recommended bucket: **Ordinary Moderate / Low-like. Borderline only under local HID injection assumptions**

## 2. Signal breakdown

Conservative signals:

* Firmware-mediated or external-device influence: +1. The affected path is driven by USB HID input from a Wacom device or a malicious HID-like device.
* Reliable kernel crash / strong DoS: +1. The commit explicitly states that GFP_KERNEL can sleep in atomic context and trigger a scheduling while atomic bug.
* Physical-only or rare hardware-only condition: -2. The direct trigger is a physical USB HID device path, not a normal remote or default local syscall path.
* Availability impact realistic: +1 not added separately. The DoS effect is already represented by the scheduling while atomic crash signal and should not be double-counted by default.

Paranoid additional interpretation:

* Local unprivileged or low-privileged trigger: +1. If a local user can access uhid, HID gadget injection, delegated device control, or a test environment that feeds HID reports into this path, the trigger becomes local rather than purely physical.
* Availability impact realistic: +1. In systems with panic_on_warn or where repeated triggering destabilizes the host, the availability impact can be host-wide and reliable.
* No memory corruption: +0. The patch only changes GFP_KERNEL to GFP_ATOMIC and does not show UAF, OOB access, overwrite, stale pointer reuse, type confusion, or refcount misuse.
* No privilege escalation plausible: +0. There is no concrete primitive beyond sleeping allocation in atomic context.
* No confidentiality or integrity impact: +0. No leak, write primitive, or security-boundary bypass is indicated.

Call-site confidence: high. The commit provides the relevant call path: wacom_raw_event -> wacom_wac_pen_serial_enforce -> wacom_wac_queue_flush, with USB HID invoking raw_event from hid_irq_in in URB completion atomic context.

## 3. Reachability analysis

The direct trigger requires a Wacom USB HID device, a malicious USB HID device, or equivalent HID-event injection that reaches the Wacom raw_event path. This is not network reachable. In typical deployments, physical device access is needed, so conservative reachability is low.

A more paranoid deployment model treats the issue as local PR:L if an untrusted local user can inject HID reports through uhid, USB gadget functionality, delegated device access, or a container or service with HID device control. That does not make the bug Important-class because the failure mode remains a scheduling while atomic DoS without memory corruption.

## 4. Severity interpretation

This behaves like a Low-like or ordinary Moderate denial-of-service issue. The realistic impact is a warning, BUG, or kernel crash depending on kernel configuration. Theoretical severity does not extend to LPE because the patch does not expose object lifetime corruption, attacker-controlled reuse, arbitrary write, or data disclosure.

The paranoid score reaches the lower Borderline range only because some systems may allow local HID injection or convert warnings into panics. It should not be treated as an Important candidate.

## 5. One-sentence report phrase

A sleepable GFP_KERNEL allocation in the Wacom HID raw_event path can execute from USB HID interrupt completion context, allowing a malicious device or local HID injection source to trigger a scheduling while atomic denial of service without evidence of memory corruption or privilege escalation.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This is a DoS-only atomic-context allocation bug with a one-line GFP_ATOMIC fix, no UAF/OOB/write primitive, no network exposure, and no plausible LPE path supported by the patch.

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

Patch: HID: wacom: use GFP_ATOMIC in wacom_wac_queue_flush()
Commit: bbe1e55629bfaabd4b2e8125b48dd3503d74ac8b
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bbe1e55629bfaabd4b2e8125b48dd3503d74ac8b

Commit description:

wacom_wac_queue_flush() is called via the .raw_event callback
(wacom_raw_event → wacom_wac_pen_serial_enforce → wacom_wac_queue_flush).
For USB HID devices, this callback is invoked from hid_irq_in(), which
is a URB completion handler running in atomic context. Using GFP_KERNEL
in this path can sleep, leading to a "scheduling while atomic" bug.

Use GFP_ATOMIC instead. The existing code already handles allocation
failure by skipping the fifo entry and continuing.

Reported-by: Sashiko-bot <sashiko-bot@kernel.org>
Fixes: 5e013ad ("HID: wacom: Remove static WACOM_PKGLEN_MAX limit")
Cc: stable@vger.kernel.org
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jinmo Yang <jinmo44.yang@gmail.com>
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/hid/wacom_sys.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=bbe1e55629bfaabd4b2e8125b48dd3503d74ac8b

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

The original Linux kernel CVE announcement for CVE-2026-68087 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68087

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:P/AC:L/PR:N/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:H
  The Best / paranoid CVSS score: 5.5

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: 1
  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: 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).