[CVE-2026-98678][LOW] iio: adc: ad4030: fix invalid oversampling_ratio validation [ Upstream

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

CVE: CVE-2026-98678
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: iio: adc: ad4030: fix invalid oversampling_ratio validation [ Upstream
Commit: 6b0cc4e32599f59c994a60743f53fc72cb2979f4
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6b0cc4e32599f59c994a60743f53fc72cb2979f4
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98678
Analysis date: Sat, 24 Oct 2026 07:04:19 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
The driver computes `ilog2()` on a non-positive oversampling value before rejecting it, but no concrete memory corruption, authorization bypass, or reliable crash is shown.

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

The original Linux kernel CVE announcement for CVE-2026-98678 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98678

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-2026-98678	LOW	https://www.kernelcve.org/list/?q=CVE-2026-98678 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE AEGIS_AS=0 LEGACY=LOW RESULT=DIFF (final Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE)	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:L/A:L';*CWE-20;CWE-682;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N';BEST CVSS score: '4.4';DESCR 'ad4030_set_avg_frame_len calculated ilog2 before validating the requested oversampling ratio. Zero or negative input could therefore reach an operation that is undefined for such values and zero could continue into device configuration with an invalid derived mode. This is an input validation and calculation ordering bug with no demonstrated memory corruption or kernel crash primitive. For the CVSS the PR:H value reflects that writing IIO device configuration attributes normally requires privileged local access. The paranoid PR:L interpretation covers deployments that delegate writable IIO controls to a less privileged service or user. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 4.4 and the production ActionableScore returned 0 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE to LOW because the ActionableScore threshold rule was applied. final reconciliation stage LOW to LOW because KP specialist did not establish a qualifying panic and the cross model evidence reconciliation rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 and KPANIC_UNSUPPORTED_REMOVED and V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 0.0 and ActionableScore 0 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	MAYBE	DANGER SIMPLEFIX LOG DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED	-	-	checked

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

ActionableScore=0
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 0.
* Conservative score: 0; no floor or cap changed it.
* Raw paranoid score: 0.
* Paranoid score: 0; unsupported device-integrity or crash effects are not scored.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +0 invalid-value concern: `ilog2(avg_val)` was evaluated before validation; zero or negative input therefore invokes an undefined calculation.
* +0 downstream invalid configuration: zero previously passed the `avg_val < 0` check, but the supplied context does not establish a concrete harmful register value, device failure, or protected-state corruption.
* No UAF, OOB access, heap overwrite, repeated lifetime mutation, authorization bypass, disclosure, or kernel crash is shown.
* No integrity or availability point: the patch does not demonstrate unauthorized protected-state modification or a reliable device/host failure.
* No privilege penalty: writable IIO controls may commonly be restricted, but the exact complete-trigger permissions are not proven.
* NEW52/B5-R and NEW53/B3-PENDING do not apply: there is no write outside an allocation or shared-backing write.

3. Reachability analysis

The input likely comes from an IIO configuration interface, but no caller, sysfs permissions, device-node policy, delegation model, or capability check is supplied. The legacy hint’s privileged-access expectation is plausible but insufficient to prove host-administrator-only reachability. Namespace-scoped access, prior privileged setup, and special hardware access requirements remain unresolved. No race or retry sequence is involved.

4. Primitive and severity reading

The exact defect is validation ordering around an undefined integer logarithm, followed in the zero case by use of an invalid derived averaging mode. This is an invalid-value/configuration bug, not demonstrated kernel memory corruption or an authorization decision bypass. Any device malfunction, kernel crash, or lasting integrity effect is speculative. Consequently there is no Important-preserving primitive, and automatic downgrade is allowed.

5. One-sentence report phrase

The driver computes `ilog2()` on a non-positive oversampling value before rejecting it, but no concrete memory corruption, authorization bypass, or reliable crash is shown.

6. Manual review advice

NO MANUAL CHECK NEEDED

The patch establishes a narrow validation-order defect without a material security primitive.

7. Call-site confidence

Call-site confidence: medium

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

Patch: iio: adc: ad4030: fix invalid oversampling_ratio validation [ Upstream
Commit: 6b0cc4e32599f59c994a60743f53fc72cb2979f4
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6b0cc4e32599f59c994a60743f53fc72cb2979f4

Changed files:
  drivers/iio/adc/ad4030.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=6b0cc4e32599f59c994a60743f53fc72cb2979f4

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

The original Linux kernel CVE announcement for CVE-2026-98678 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98678

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:L/A:N
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
  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: unknown
  Paranoid ActionableScore: 0

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).