[CVE-2026-80930][LOW] tpm: tpm_i2c_nuvoton: disable IRQ on wait timeout

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

CVE: CVE-2026-80930
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: tpm: tpm_i2c_nuvoton: disable IRQ on wait timeout
Commit: 73e89faee1f9b9119fa70b679058b045168ae633
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=73e89faee1f9b9119fa70b679058b045168ae633
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80930
Analysis date: Fri, 11 Sep 2026 16:34:55 -0400
ActionableScore: 2
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-2026-80930 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80930

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-2026-80930	LOW	https://www.kernelcve.org/list/?q=CVE-2026-80930 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-404;*CWE-664;CWE-755;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'The Nuvoton I2C TPM driver can leave an IRQ enabled when i2c_nuvoton_wait_for_stat() exits after a timeout or an interrupted wait before the interrupt handler reports the expected status change. This creates an IRQ state imbalance and can cause incorrect TPM driver behavior, warnings, extra interrupts, or loss of TPM availability. For the CVSS the PR:L is used because a local user or process needs access to the TPM device path or a TPM using service context to trigger the affected wait path. The issue is not network reachable and does not show a memory corruption primitive. Impact is denial of service only, mainly affecting TPM device availability rather than confidentiality or integrity.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	YES	USB SIMPLEFIX LINUS TEST  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH	NO	NO	checked

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

ActionableScore=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 2
* Conservative score: 2. No floor or cap applied.
* Raw paranoid score: 2
* Paranoid score: 2. No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

Positive signals:

* +1 Concrete IRQ lifecycle imbalance. The function enables the IRQ before waiting, and the failed wait path returned without the matching disable_irq().
* +1 Local below-host-admin reachability. The affected path is reachable by local TPM users or TPM-using service contexts with access to the TPM device, not necessarily by host administrators only.

Non-awarded signals:

* RealUAF not awarded. No freed object or stale post-lifetime object use is established.
* Concrete repeated release/refcount not awarded. There is no first release that may end lifetime followed by a second release on the same dangling reference.
* Controlled reclaim, arbitrary write, OOB access, callback control, and memory corruption are not demonstrated.
* Remote reachability not awarded. This is a local TPM driver path, not a network-triggered path.
* Extra availability not awarded. The likely consequence is TPM driver or TPM device availability degradation, not a demonstrated host-wide crash.
* C/I impact not awarded. No confidentiality or integrity primitive is established.

Negative signals:

* No privilege penalty applied because host-admin-equivalent privilege is not positively established.
* No race/timing penalty applied. Timeout or interrupted wait is a condition, but the scoring does not require a narrow attacker-controlled race.
* No rare-hardware penalty applied. This is hardware-specific TPM driver code, but the evidence does not establish rare physical-only attack conditions beyond use of the affected device.

3. Reachability analysis

The evaluated attacker is a local process that can issue TPM operations through the Nuvoton I2C TPM driver path, either directly via the TPM device node or indirectly through a TPM-using service context. This is below host-admin in plausible deployments, although actual device-node permissions may vary by distribution and policy.

The issue is not namespace-scoped. User namespaces or network namespaces are not relevant to the complete trigger chain.

No network reachability is established. No prior special host setup is shown beyond having the affected TPM hardware and driver active. The relevant failure requires a wait timeout or interrupted wait before the interrupt handler reports the expected status change. This is a reliability condition but not a concrete memory-corruption race.

4. Primitive and severity interpretation

The exact primitive is an IRQ enable/disable imbalance in the failed wait path of i2c_nuvoton_wait_for_stat(). The bug class is invalid resource or lifecycle state management, not memory corruption.

This is not an active structured UAF and not fixed stale storage. There is no cleanup/destructor stale dereference and no broader post-free object use. There is also no concrete repeated release/refcount operation.

PrimitiveClass=CLASS_C because the demonstrated behavior is invalid driver state and potential local DoS without an independently useful corruption primitive. The demonstrated consequence is incorrect TPM driver behavior, warnings, extra interrupts, timeout-related malfunction, or TPM availability loss. A stronger system-wide crash or privilege escalation is speculative and not supported by the patch.

ImportantCandidate=NO because no Class A or meaningful unresolved Class B primitive exists. AutoDowngradeAllowed=YES because this is a constrained local device/driver availability issue without UAF, boundary bypass, C/I impact, or memory corruption leverage.

Likely operational severity is Low to ordinary Moderate.

5. One-sentence report phrase

The Nuvoton I2C TPM driver may leave an IRQ enabled after a timed out or interrupted wait, causing an IRQ state imbalance and potential local TPM availability loss without evidence of memory corruption or privilege escalation.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: the patch shows a local IRQ balancing bug with DoS-only impact, no UAF, no repeated lifetime mutation, no authorization bypass, and no network exposure.

7. Call-site confidence

Call-site confidence: medium

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

Patch: tpm: tpm_i2c_nuvoton: disable IRQ on wait timeout
Commit: 73e89faee1f9b9119fa70b679058b045168ae633
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=73e89faee1f9b9119fa70b679058b045168ae633

Commit description:

i2c_nuvoton_wait_for_stat() enables the IRQ before waiting for the
interrupt handler to report a status change. If the wait times out, or is
interrupted before the handler runs, the function returns without
balancing the enable_irq() call.

Disable the IRQ before leaving the failed wait path. Also preserve an
interrupted wait's original error code instead of converting it to
-ETIMEDOUT inside the helper.

Cc: stable@vger.kernel.org # v5.10+
Fixes: 4c336e4 ("tpm: Add support for the Nuvoton NPCT501 I2C TPM")
Co-developed-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lore.kernel.org/r/20260626091653.54929-1-mhun512@gmail.com
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/char/tpm/tpm_i2c_nuvoton.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=73e89faee1f9b9119fa70b679058b045168ae633

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

The original Linux kernel CVE announcement for CVE-2026-80930 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80930

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:L/UI:N/S:U/C:N/I:N/A:L
  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: 2

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).