[CVE-2026-80611][LOW] ACPI: processor_idle: Mark LPI enter functions as __cpuidle [ Upstream

[CVE-2026-80611][LOW] ACPI: processor_idle: Mark LPI enter functions as __cpuidle [ Upstream

[AL-KERNEL]

CVE: CVE-2026-80611
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: ACPI: processor_idle: Mark LPI enter functions as __cpuidle [ Upstream
Commit: 10f675902a5fc88ccfe34bb8aa37de50806b03b1
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=10f675902a5fc88ccfe34bb8aa37de50806b03b1
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80611
Analysis date: Fri, 28 Aug 2026 04:14:11 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
ACPI LPI idle entry functions could be instrumented by ftrace or kprobes after RCU was disabled on the local CPU, causing RCU warnings during idle entry, but triggering normally requires privileged tracing access and no memory corruption or privilege escalation primitive is shown.

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

The original Linux kernel CVE announcement for CVE-2026-80611 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80611

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-2026-80611	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:L';CWE-703;CWE-754;CWE-693;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '3.3';DESCR 'ACPI LPI idle entry functions could be traced even though they run in the cpuidle path after RCU has been disabled on the local CPU. When function tracing or kprobes are enabled, ftrace can enter function_trace_call while RCU is not watching and emit RCU warnings during idle entry. For the CVSS the PR:L is used only for the paranoid score to cover deployments where tracing control is delegated to a less trusted local operator. In the normal base case PR:H is more realistic because enabling ftrace or kprobes usually requires administrator privileges. The issue is not network reachable and is not triggered by packet traffic. Impact is limited to warnings, possible log noise, and low availability degradation. There is no evidence of memory corruption, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)	YES	OOB SIMPLEFIX HARDWARE  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	checked

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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:

* WARN / validation state concern: +1
  The patch prevents ftrace or kprobes from instrumenting ACPI LPI idle entry after RCU is already disabled. The observed failure is an RCU splat and WARNING, not a concrete crash, UAF, OOB access, or privilege boundary bypass.

* Availability impact realistic: +0 conservative, +1 paranoid
  Conservative scoring does not count this as strong DoS because the commit shows WARN output, not a reliable panic or system-wide failure. Paranoid scoring gives +1 for possible operational impact from repeated warnings or tracing-induced instability on affected systems.

Negative or limiting signals:

* Requires admin/root/CAP_SYS_ADMIN in typical deployments: -2
  Enabling ftrace or kprobes is normally restricted to root or privileged tracing/debug access.

* Special runtime condition: -1
  The issue requires function tracing or kprobes to be enabled and an ACPI LPI cpuidle path to be exercised.

Not triggered:

* Remote reachable: +0
  No network path.

* Local unprivileged trigger: +0
  Ordinary unprivileged users normally cannot enable the required tracing or kprobe instrumentation.

* Generic memory corruption: +0
  No UAF, double-free, OOB write, type confusion, refcount misuse, or stale pointer primitive is shown.

* Privilege escalation plausible: +0
  The patch only prevents tracing instrumentation in a no-RCU idle context.

## 3. Reachability analysis

The bug is triggered when ACPI LPI idle entry functions are instrumented by ftrace or kprobes while the CPU enters the cpuidle path after RCU has stopped watching. In typical deployments, controlling ftrace or kprobes requires administrator privileges, usually root or CAP_SYS_ADMIN through tracefs or debug facilities.

Namespaces and containers generally do not make this meaningfully unprivileged unless tracing control is explicitly delegated to a less trusted local operator. The path is not network reachable and is not triggered by packet traffic. Realistic exploitation conditions require both affected ACPI LPI idle support and enabled tracing or kprobe instrumentation.

Call-site confidence: high, because the affected functions and the cpuidle context are directly visible in the supplied patch and commit message.

## 4. Severity interpretation

This behaves like a Low or ordinary Moderate correctness issue, not an actionable Moderate or Important-class vulnerability. The realistic impact is an RCU warning during idle entry under tracing conditions. There is no demonstrated kernel memory corruption, no sensitive data exposure, no integrity impact, and no practical privilege escalation path.

Theoretical risk is limited to debugging or tracing instability. The patch context does not support upgrading this into UAF, arbitrary write, or security-boundary bypass.

## 5. One-sentence report phrase

ACPI LPI idle entry functions could be instrumented by ftrace or kprobes after RCU was disabled on the local CPU, causing RCU warnings during idle entry, but triggering normally requires privileged tracing access and no memory corruption or privilege escalation primitive is shown.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed for security triage unless the affected product explicitly delegates ftrace or kprobe control to untrusted local users or treats kernel WARN output as a production-impacting availability issue.

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

Patch: ACPI: processor_idle: Mark LPI enter functions as __cpuidle [ Upstream
Commit: 10f675902a5fc88ccfe34bb8aa37de50806b03b1
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=10f675902a5fc88ccfe34bb8aa37de50806b03b1

Changed files:
  include/linux/trace_recursion.h
  drivers/acpi/processor_idle.c
  drivers/acpi/riscv/cpuidle.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=10f675902a5fc88ccfe34bb8aa37de50806b03b1

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

The original Linux kernel CVE announcement for CVE-2026-80611 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80611

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:L/PR:H/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:L
  The Best / paranoid CVSS score: 3.3

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).