[CVE-2026-80639][LOW] cxl/test: Fix __fortify_panic [ Upstream

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

CVE: CVE-2026-80639
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: cxl/test: Fix __fortify_panic [ Upstream
Commit: 8c4f27a7f364eab514d2fa55c11f39d505122f1b
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8c4f27a7f364eab514d2fa55c11f39d505122f1b
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80639
Analysis date: Fri, 28 Aug 2026 05:01:41 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-80639 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80639

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-2026-80639	LOW	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';CWE-665;CWE-617;CWE-754;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.4';DESCR 'A FORTIFY runtime assertion can be triggered in the cxl/test cxl_translate module because the counted_by field nr_maps is initialized after memcpy into the xormaps flexible array. This makes the destination appear to have size 0 to the hardened bounds checks and can result in __fortify_panic during module load. For the CVSS the PR:H because triggering normally requires administrative ability to load the kernel test module. The issue is not network reachable and is limited to local test or development systems where this module is built and loaded. Impact is denial of service through a warning or possible kernel panic, with no supported evidence of information disclosure, integrity impact, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)  SKIP CVE-2026-80639 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	OOB INIT SIMPLEFIX HARDWARE TEST  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScoreLower=0
ActionableScore=1

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

2. Signal breakdown
* Reliable kernel crash / strong DoS: +1 only for paranoid scoring. The trace shows `__fortify_panic` during `modprobe`, so a panic or forced module-load failure is possible depending on hardening and panic behavior.
* Requires admin/root/CAP_SYS_MODULE in typical deployments: -2. Triggering requires loading the `cxl_translate` kernel test module.
* Rare AND difficult-to-reach subsystem/configuration: -1. The affected code is under `tools/testing/cxl/test`, not a broadly exposed production kernel path.
* No memory corruption primitive: +0. The commit explicitly describes this as a FORTIFY false positive caused by `__counted_by(nr_maps)` metadata being initialized after `memcpy`.
* No confidentiality or integrity signal: +0. There is no UAF, OOB write with real target corruption, arbitrary write, info leak, or privilege escalation path supported by the patch.

3. Reachability analysis
The bug is locally reachable only by a user able to load the CXL test module, normally root or a process with equivalent module-loading privileges. Namespaces do not normally lower this requirement because kernel module loading is host-global and privileged. The path is not default network-exposed and is limited to test or development configurations where `cxl_translate` is built and loaded.

4. Severity interpretation
This behaves like a Low-like or ordinary Moderate robustness issue, not an Important kernel vulnerability. The realistic impact is a local privileged FORTIFY assertion or possible panic during test module load. Theoretical memory corruption is not supported because the patch only reorders initialization of `nr_maps` before `memcpy` so the counted flexible array metadata matches the already intended allocation layout.

5. One-sentence report phrase
A FORTIFY runtime assertion in the CXL test module can be triggered during privileged module load because `nr_maps` is initialized after copying into the counted `xormaps` array, causing a local privileged DoS risk only in test or development configurations.

6. Manual review recommendation
NO MANUAL CHECK NEEDED
This can be auto-closed for security triage unless the affected product ships and auto-loads this test module in production.

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

Patch: cxl/test: Fix __fortify_panic [ Upstream
Commit: 8c4f27a7f364eab514d2fa55c11f39d505122f1b
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8c4f27a7f364eab514d2fa55c11f39d505122f1b

Changed files:
  lib/string_helpers.c
  tools/testing/cxl/test/cxl_translate.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=8c4f27a7f364eab514d2fa55c11f39d505122f1b

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

The original Linux kernel CVE announcement for CVE-2026-80639 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80639

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:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.4

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).