[CVE-2026-89620][IMPORTANT] HID: intel-thc-hid: intel-quickspi: validate report size before copy

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

CVE: CVE-2026-89620
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: HID: intel-thc-hid: intel-quickspi: validate report size before copy
Commit: 6fcefe71aeb524f6e77fe586fe85d873745e917c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6fcefe71aeb524f6e77fe586fe85d873745e917c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89620
Analysis date: Fri, 11 Sep 2026 20:22:37 -0400
ActionableScore: 7
ActionableScore lower bound: unknown
Actionable bucket: Strong Important candidate
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-89620 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89620

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-2026-89620	IMPORTANT	https://www.kernelcve.org/list/?q=CVE-2026-89620 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:H/I:H/A:H';*CWE-787;CWE-122;*CWE-20;BEST CVSS score: '7.8';DESCR 'A heap buffer overflow exists in the HID intel quickspi driver because write_cmd_to_txdma can copy a caller supplied HID report into qsdev report_buf without validating that the report plus output header fits the allocated buffer. A local attacker with access to the affected hidraw device can trigger this through an oversized SET_REPORT or SET_FEATURE request, with attacker controlled length and content reaching the kernel heap copy. For the CVSS the PR:L value is used because reliable triggering requires local access to the hidraw device but does not require full administrator privileges in deployments where such device nodes are exposed to logged in users or device groups. The issue is not network reachable and requires an affected Intel THC QuickSPI HID device. Impact includes kernel crash and a plausible local privilege escalation path because the primitive is an out of bounds heap write with controlled data.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate (with actual score 7)	YES	WRITE OOB USB HARDWARE KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS	YES	NO	checked

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

ActionableScore=7
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

1. ActionableScore

* Raw conservative score: 6
* Conservative score: 7
* Raw paranoid score: 7
* Paranoid score: 7
* Applied conservative floor/cap: 6 -> 7 due to Class A Important preservation for attacker-controlled kernel heap overwrite reachable below host-admin-equivalent privilege.
* Final recommended bucket: **Strong Important candidate**::

2. Signal breakdown

Positive signals:

* +2 Strong corruption primitive: `write_cmd_to_txdma()` copies attacker-supplied HID report data into `qsdev->report_buf` without validating that `report_buf_len` plus the output header fits the allocated buffer.
* +1 Local below-host-admin trigger: the trigger is a local `hidraw` `SET_REPORT` or `SET_FEATURE` ioctl by a process with access to the affected hidraw node, not host-admin-equivalent privilege in the relevant attacker model.
* +1 Local high-control kernel device API: attacker controls the report length and report contents reaching the kernel heap `memcpy()`.
* +1 Reliable kernel crash / strong DoS: oversized reports can corrupt kernel heap memory and realistically crash the kernel.
* +1 Integrity plausible: controlled out-of-bounds heap write can modify adjacent protected kernel heap state.
* +1 Paranoid strong exploitation interpretation: the overwrite is attacker-controlled and large relative to the expected few-hundred-byte device report buffer, so local privilege escalation is a technically defensible concern requiring review.

Non-awarded signals:

* RealUAF not awarded: this is an out-of-bounds heap write, not a lifetime or stale-reference bug.
* Remote reachability not awarded: the trigger is local hidraw ioctl access, not network traffic.
* Controlled reclaim not demonstrated.
* Arbitrary read/write not demonstrated.
* Confidentiality not awarded: no disclosure or read-back path is established.
* Extra availability not awarded: crash and availability are the same consequence.
* Hardware rarity penalty not applied: the affected path is device-specific, but the supplied evidence does not establish rare or physical-only attacker requirements.
* Race/timing penalty not applied: the bug is a direct bounds-check failure, not a timing race.

3. Reachability analysis

The evaluated attacker is a local process that can open and write to the affected `/dev/hidrawX` node for an Intel THC QuickSPI HID device. The complete trigger is a `SET_REPORT` or `SET_FEATURE` operation carrying a report larger than the device-descriptor-derived `max_report_len`. This does not require network access and is not namespace-scoped.

Host-admin-equivalent privilege is not positively required by the primitive. Practical reachability depends on device-node permissions, desktop seat policy, udev rules, or membership in a device/input-related group. If a product restricts the hidraw node to root only, deployment risk is lower, but the vulnerability itself is a below-host-admin local device-interface corruption issue when hidraw access is exposed.

A prior affected hardware and driver presence is required. No special race, boot option, firmware compromise, or remote setup is established.

4. Primitive and severity interpretation

The exact primitive is an attacker-controlled kernel heap out-of-bounds write. The vulnerable allocation used `max_report_len`, while the write path builds an output report containing a header plus caller-controlled content and then copies `report_buf_len` bytes into the content area. Because HID core can pass reports up to `HID_MAX_BUFFER_SIZE` and this driver did not set a smaller `max_buffer_size`, a report much larger than the allocated QuickSPI report buffer can reach the `memcpy()`.

This is not fixed stale storage, not cleanup-only behavior, and not a resource leak. It is a direct active heap memory corruption primitive with controlled data and controlled length. Demonstrated consequence includes kernel memory corruption and likely crash. Speculative but technically plausible consequence includes local privilege escalation through heap object corruption, although no controlled reclaim, arbitrary kernel read/write, or working exploit chain is supplied.

PrimitiveClass is CLASS_A because the patch establishes a controlled heap overwrite. ImportantCandidate is YES because this is an Important-preserving kernel memory corruption primitive. AutoDowngradeAllowed is NO because automatically closing or downgrading would lose a concrete controlled kernel corruption issue with unresolved exploitation leverage.

Likely operational severity is Strong Important candidate for affected systems where untrusted or semi-trusted local users can access the relevant hidraw device.

5. One-sentence report phrase

A local attacker with access to the affected Intel QuickSPI HID hidraw device can send an oversized SET_REPORT or SET_FEATURE request that overflows a kernel heap report buffer with controlled content, causing DoS and creating a plausible local privilege escalation risk.

6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the patch fixes a concrete attacker-controlled kernel heap out-of-bounds write, and the practical exploitability depends on local hidraw exposure and heap corruption leverage.

7. Call-site confidence

Call-site confidence: high

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

Patch: HID: intel-thc-hid: intel-quickspi: validate report size before copy
Commit: 6fcefe71aeb524f6e77fe586fe85d873745e917c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6fcefe71aeb524f6e77fe586fe85d873745e917c

Commit description:

write_cmd_to_txdma() builds an output report in qsdev->report_buf, a heap
buffer allocated in quickspi_alloc_report_buf() to the device-descriptor
derived max_report_len (a few hundred bytes for a touch controller).  It
copies the caller-supplied report into that buffer:

    memcpy(write_buf->content, report_buf, report_buf_len);

The HID core caps a report at HID_MAX_BUFFER_SIZE (16384) by default, and
quickspi_hid_ll_driver does not set max_buffer_size, so the length reaches
the driver unbounded.  A hidraw SET_REPORT/SET_FEATURE ioctl carrying a
report larger than max_report_len therefore overflows report_buf with
attacker-controlled length and content.

Record the report_buf allocation size and reject reports that do not fit
before copying, matching the equivalent guard in the intel-quicki2c
sibling (quicki2c_init_write_buf()) and the hid-goodix-spi fix.

write_cmd_to_txdma() writes the output report header ahead of the content
in the same buffer, so size the allocation to cover the header as well.
That keeps the added bound from rejecting a maximum-sized report.

Fixes: 9d8d517 ("HID: intel-thc-hid: intel-quickspi: Add HIDSPI protocol implementation")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
Reviewed-by: Even Xu <even.xu@intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/hid/intel-thc-hid/intel-quickspi/pci-quickspi.c
  drivers/hid/intel-thc-hid/intel-quickspi/quickspi-dev.h
  drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.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=6fcefe71aeb524f6e77fe586fe85d873745e917c

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

The original Linux kernel CVE announcement for CVE-2026-89620 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89620

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:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 7

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: YES
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).