[CVE-2026-97980][LOW] s390/debug: Fix NULL pointer dereference in debug_set_level() [ Upstream

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

CVE: CVE-2026-97980
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: s390/debug: Fix NULL pointer dereference in debug_set_level() [ Upstream
Commit: 716e1cd3783806929407dbd596e6b1118971eb9e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=716e1cd3783806929407dbd596e6b1118971eb9e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97980
Analysis date: Fri, 25 Sep 2026 11:27:09 -0400
ActionableScore: 1
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-2026-97980 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97980

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-2026-97980	LOW	https://www.kernelcve.org/list/?q=CVE-2026-97980 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-476;CWE-690;CWE-252;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'A NULL pointer dereference can occur in the s390 debug API when debug_register returns NULL and a kernel API user passes that result directly to debug_set_level. The wrapper accesses id name through debug_get_param before the internal NULL check can run, which can cause a kernel Oops or panic. Triggering requires a relevant s390 debug API caller and a debug registration failure, such as one caused by initialization failure or memory pressure, so attack complexity is high. For the CVSS the PR:L value is used in the paranoid score because a local user may be able to influence resource pressure or reach an existing component initialization path without having full administrative control. The base score uses PR:H because direct control over module or component initialization is the more realistic trigger. The issue is not network reachable based on the available call path. Impact is local denial of service only, with no supported UAF, out of bounds access, information disclosure, or privilege escalation primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)  SKIP CVE-2026-97980 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES  NO NO unknown 	MAYBE	DANGER NULLPTR SIMPLEFIX HARDWARE LINUS  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* No floor or cap was applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Reliable kernel crash or strong DoS. A NULL result from `debug_register()` reaches `debug_get_param(id->name, ...)`, causing a NULL dereference and potentially an Oops or panic.
* No UAF, stale lifetime operation, repeated release, overwrite, disclosure, authorization bypass, or semantic reinterpretation is established.
* No local-unprivileged bonus. Userspace cannot call `debug_set_level()` directly, and the complete trigger through a vulnerable debug-API caller is not shown.
* No privilege penalty. Host-admin-equivalent privilege is not positively established.
* No remote-reachability bonus. This is an internal s390 kernel API path.
* No additional Availability point because it would duplicate the same possible crash.
* No s390 rarity penalty because architecture specialization alone is insufficient.

3. Reachability analysis

The trigger requires an s390 debug-API user to pass an unchecked NULL result from `debug_register()` to `debug_set_level()`. A registration failure such as allocation failure is also required. The supplied evidence does not identify a userspace-controlled caller, capability check, namespace path, prior privileged setup, or remotely reachable interface.

Consequently, both the host privilege requirement and any namespace-scoped reachability remain unresolved. There is no timing race or special hardware prerequisite beyond running on s390.

4. Primitive and severity interpretation

The exact primitive is a NULL pointer read through `id->name`. It is an invalid-dereference Class C issue, not a UAF or other lifetime violation. There is no active stale object, repeated release, refcount mutation, controlled reclaim, attacker-selected target, or write primitive.

The demonstrated consequence is a possible kernel Oops or panic. Information disclosure, integrity impact, privilege escalation, and exploitation leverage beyond the crash are unsupported. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` because no unresolved corruption or security-boundary primitive exists.

5. One-sentence report phrase

An unchecked NULL result from s390 debug registration can reach `debug_set_level()` and cause a kernel Oops or panic, but no memory corruption or privilege escalation primitive is established.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

This is a narrowly defined architecture-specific NULL dereference with crash-only impact and no demonstrated attacker-accessible security primitive.

7. Call-site confidence

Call-site confidence: medium

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

Patch: s390/debug: Fix NULL pointer dereference in debug_set_level() [ Upstream
Commit: 716e1cd3783806929407dbd596e6b1118971eb9e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=716e1cd3783806929407dbd596e6b1118971eb9e

Changed files:
  arch/s390/kernel/debug.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=716e1cd3783806929407dbd596e6b1118971eb9e

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

The original Linux kernel CVE announcement for CVE-2026-97980 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97980

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:H/UI:N/S:U/C:N/I:N/A:H
  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: 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).