[CVE-2026-72152][LOW] tpm: tpm_tis_spi: Use wait_woken() in wait_for_tmp_stat()

[CVE-2026-72152][LOW] tpm: tpm_tis_spi: Use wait_woken() in wait_for_tmp_stat()

[AL-KERNEL]

CVE: CVE-2026-72152
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: tpm: tpm_tis_spi: Use wait_woken() in wait_for_tmp_stat()
Commit: c9acbe38797bc1aa3c22a1ab72452e210af6e0ff
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c9acbe38797bc1aa3c22a1ab72452e210af6e0ff
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72152
Analysis date: Sat, 15 Aug 2026 23:43:38 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
`tpm_tis_spi may evaluate a TPM status condition after entering TASK_INTERRUPTIBLE, causing a debug atomic sleep warning through the SPI mutex path, with impact limited to local availability on affected TPM SPI and debug or panic_on_warn configurations.`

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

The original Linux kernel CVE announcement for CVE-2026-72152 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72152

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-2026-72152	LOW	CHECK WITH IMPACT FROM ORIG NN LOW	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-667;CWE-703;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 'tpm_tis_spi can evaluate the TPM status condition after the task has already been set to TASK_INTERRUPTIBLE by wait_event_interruptible_timeout. The condition path may perform SPI I/O and take a mutex through spi_bus_lock, which triggers a sleep in an invalid task state warning when CONFIG_DEBUG_ATOMIC_SLEEP is enabled and the IRQ wait path is used. For the CVSS the PR:L is selected because a local process needs access to TPM operations or a TPM using service that can drive this wait path, but no administrative privileges are normally implied by the code path itself. The issue is not network reachable and no memory corruption primitive is indicated. Impact is limited to local availability through warnings or possible disruption on debug kernels or systems configured to panic on warnings.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)	YES	OOB DMAorINTERRUPT  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	checked

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

ActionableScore=1
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Triggered signals:

* Local trigger possible: +1
  A local process or TPM-using service can potentially drive TPM operations that reach `wait_for_tpm_stat()`. This is not a network path.

* Availability impact realistic only in paranoid interpretation: +1
  The demonstrated effect is a `CONFIG_DEBUG_ATOMIC_SLEEP` warning. It may become disruptive only on debug kernels or systems configured with fatal warning behavior such as `panic_on_warn`.

Subtracting signals:

* Non-default/debug-sensitive failure mode: -1
  The concrete reported symptom depends on `CONFIG_DEBUG_ATOMIC_SLEEP`, which is primarily a debug configuration.

* Rare or hardware-specific path: -1 conservative
  The issue is specific to TPM TIS SPI IRQ wait handling, not a broad default kernel data path.

Not triggered:

* No remote reachability.
* No generic memory corruption.
* No UAF, OOB write, double free, type confusion, refcount abuse, or stale callback.
* No plausible privilege escalation primitive.
* No confidentiality or integrity impact.

## 3. Reachability analysis

The bug is reachable through the TPM TIS SPI driver when IRQ-based waiting is used. A local user or local service that can issue TPM operations may be able to exercise the path, depending on device permissions such as access to `/dev/tpm0` or `/dev/tpmrm0`.

Namespaces and containers do not materially increase exposure unless TPM device nodes are explicitly passed through. The path is not network reachable. The practical failure mode is mostly relevant to debug kernels or systems where warnings are treated as fatal.

Call-site confidence: high, because the patch and commit message provide the direct call chain from `wait_for_tpm_stat()` to `spi_bus_lock()` and `mutex_lock()`.

## 4. Severity interpretation

This behaves like a Low-like or ordinary Moderate reliability issue, not an Important-class vulnerability. The patch fixes an invalid sleep-context pattern caused by evaluating the wait condition after the task state was changed to `TASK_INTERRUPTIBLE`.

There is no evidence of memory lifetime corruption, attacker-controlled object reuse, write primitive, sensitive data exposure, or privilege escalation. The theoretical worst case is local availability impact if the warning becomes fatal, but the realistic demonstrated impact is a debug warning.

## 5. One-sentence report phrase

`tpm_tis_spi may evaluate a TPM status condition after entering TASK_INTERRUPTIBLE, causing a debug atomic sleep warning through the SPI mutex path, with impact limited to local availability on affected TPM SPI and debug or panic_on_warn configurations.`

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed for urgent security triage because it is local, hardware/configuration dependent, warning-oriented, and shows no memory corruption or privilege escalation primitive.

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

Patch: tpm: tpm_tis_spi: Use wait_woken() in wait_for_tmp_stat()
Commit: c9acbe38797bc1aa3c22a1ab72452e210af6e0ff
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c9acbe38797bc1aa3c22a1ab72452e210af6e0ff

Commit description:

wait_event_interruptible_timeout() evaluates its condition after setting
the current task state to TASK_INTERRUPTIBLE.

With CONFIG_DEBUG_ATOMIC_SLEEP this triggers a warning when the IRQ wait
path is used:

    tpm_tis_status()
      tpm_tis_spi_read_bytes()
        tpm_tis_spi_transfer_full()
          spi_bus_lock()
            mutex_lock()

Address this with the following measures:

1. Call wait_tpm_stat_cond() only while tasking is running.
2. Use wait_woken() to wait for changes.

Cc: stable@vger.kernel.org # v4.19+
Cc: Linus Walleij <linusw@kernel.org>
Reported-by: Stefan Wahren <wahrenst@gmx.net>
Closes: https://lore.kernel.org/linux-integrity/6964bec7-3dbb-453b-89ef-9b990217a8b9@gmx.net/
Fixes: 1a339b6 ("tpm_tis_spi: Pass the SPI IRQ down to the driver")
Reviewed-by: Linus Walleij <linusw@kernel.org>
Tested-by: Stefan Wahren <wahrenst@gmx.net>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/char/tpm/tpm_tis_core.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=c9acbe38797bc1aa3c22a1ab72452e210af6e0ff

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

The original Linux kernel CVE announcement for CVE-2026-72152 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72152

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: 0
  Paranoid ActionableScore: 1

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).