[CVE-2026-45941][LOW] tpm: tpm_i2c_infineon: Fix locality leak on get_burstcount() failure [ Upstream

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

CVE: CVE-2026-45941
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: tpm: tpm_i2c_infineon: Fix locality leak on get_burstcount() failure [ Upstream
Commit: 8f124c5582d443ac9fb690db26d08cab5d6ba76e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8f124c5582d443ac9fb690db26d08cab5d6ba76e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45941
Analysis date: Wed, 27 May 2026 20:20:25 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A cleanup error in tpm_i2c_infineon can leak an acquired TPM locality when get_burstcount() fails, causing a local TPM service denial of service on affected Infineon I2C TPM systems.

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

The original Linux kernel CVE announcement for CVE-2026-45941 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45941

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-2026-45941	LOW	CHECK	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-772;CWE-404;CWE-703;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A cleanup bug in tpm_i2c_infineon can leave a TPM locality acquired when get_burstcount() fails with a timeout or busy error during tpm_tis_i2c_send(). This can make later TPM operations fail or hang because the locality was not released, causing a TPM service denial of service rather than a kernel memory corruption issue. For the CVSS the PR:L is used because local access to the TPM character device or TPM resource manager may be delegated to a user or service, while full administrator privileges are not inherently required in all deployments. The issue is not network reachable and usually also depends on a device busy or timeout condition, so reliable triggering is not straightforward. Impact is limited to availability of TPM functionality, with no supported evidence of confidentiality impact, integrity impact, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2) 	MAYBE	USB SIMPLEFIX LEAK IMPROVEONLY LINUS 	-	-	checked

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

ActionableScore=2
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**::

## 2. Signal breakdown

* Local unprivileged trigger: +1
  Possible only if local users or services can access the TPM character device or TPM resource manager. In many systems this access is restricted or mediated.

* Reliable kernel crash / strong DoS: +0
  The patch does not show a kernel crash, memory corruption, or panic. The likely effect is TPM locality/resource leakage causing later TPM operations to fail or hang.

* Availability impact realistic: +1 in paranoid scoring only
  Availability impact is limited to TPM functionality. It may affect measured boot, attestation, sealing, or TPM-backed workflows, but not general kernel availability.

* Hard or unreliable timing/device condition: -1
  Triggering requires get_burstcount() to fail with timeout or busy state after locality acquisition, so it depends on device state or timing rather than a simple deterministic software path.

* Rare AND difficult-to-reach subsystem/configuration: -1 conservative
  This is specific to the Infineon I2C TIS TPM driver and requires affected hardware or platform configuration.

* No memory corruption: +0
  The bug is a cleanup/resource-release error. No UAF, double-free, OOB write, arbitrary write, or page-cache corruption is indicated.

* No privilege escalation or confidentiality impact: +0
  The leaked locality can deny TPM service, but the patch does not imply key disclosure, credential theft, bypass of TPM authorization, or LPE.

## 3. Reachability analysis

The bug is reachable from local TPM command submission paths if the affected Infineon I2C TPM driver is present and userspace can send TPM commands. Namespaces generally do not make this broadly reachable unless the TPM device is deliberately passed into a container or exposed to an untrusted service. The path is not network reachable. Realistic triggering depends on a timeout or busy condition in get_burstcount(), so exploitation is less reliable than ordinary local syscall DoS.

## 4. Severity interpretation

This behaves like Low or ordinary Moderate. The realistic impact is denial of service for TPM operations due to a leaked locality, not system-wide kernel compromise. There is no demonstrated memory corruption, no sensitive-object access, and no practical privilege escalation path. The paranoid score only accounts for TPM availability being operationally important in some environments.

## 5. One-sentence report phrase

A cleanup error in tpm_i2c_infineon can leak an acquired TPM locality when get_burstcount() fails, causing a local TPM service denial of service on affected Infineon I2C TPM systems.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

The issue is hardware and driver specific, requires local TPM access plus a timeout or busy condition, and shows no memory corruption or privilege escalation primitive.

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

Patch: tpm: tpm_i2c_infineon: Fix locality leak on get_burstcount() failure [ Upstream
Commit: 8f124c5582d443ac9fb690db26d08cab5d6ba76e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8f124c5582d443ac9fb690db26d08cab5d6ba76e

Changed files:
  drivers/char/tpm/tpm_i2c_infineon.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=8f124c5582d443ac9fb690db26d08cab5d6ba76e

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

The original Linux kernel CVE announcement for CVE-2026-45941 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45941

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: 1
  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).