[CVE-2026-98825][MODERATE REGULAR] rtc: mpfs: fix unchecked devm_clk_get() error pointer in probe() [ Upstream

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

CVE: CVE-2026-98825
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: rtc: mpfs: fix unchecked devm_clk_get() error pointer in probe() [ Upstream
Commit: 74dc7c52946e3d47c40edd0875adb7cc15937066
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=74dc7c52946e3d47c40edd0875adb7cc15937066
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98825
Analysis date: Fri, 23 Oct 2026 19:39:33 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
The Microchip PolarFire SoC RTC probe can dereference an error pointer returned for an unavailable rtcref clock and cause a kernel Oops, but the issue requires specialized hardware and exposes no unprivileged, network, memory-corruption, or authorization-bypass primitive.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-98825 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98825

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: MODERATE REGULAR
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-98825	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98825 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE RESULT=DIFF V39_AEGIS_ONE_STEP_UP=LOW->MODERATE TEMP_DISTANCE_MERGE_SKIP=AEGIS_NO_POSITIVE_SEVERITY_EVIDENCE (final Legacy and Aegis differ; FINAL: MODERATE, Aegis: MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-252;CWE-754;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.1';DESCR 'The Microchip PolarFire SoC RTC driver can pass an ERR_PTR returned by devm_clk_get directly to clk_get_rate during device probe. If the rtcref clock provider is not ready, devm_clk_get can return EPROBE_DEFER and clk_get_rate can dereference the invalid clock pointer, causing an Oops or kernel crash instead of deferring the probe. For the CVSS the PR:H value is used because reliable attacker controlled triggering would normally require administrative control over driver loading, device reprobe, or the platform device state. The issue is local and hardware specific, with no network reachable path. The demonstrated impact is availability loss only. Confidentiality and integrity impact are not supported because the invalid pointer is only dereferenced for a read and no controlled memory corruption primitive is present. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 4.1 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 MODERATE because 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 V39_AEGIS_ONE_STEP_UP and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 1.9 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	MAYBE	DANGER HARDWARE LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 V39_AEGIS_ONE_STEP_UP MANUAL_REVIEW_REQUIRED	-	-	checked

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

1. ActionableScore

* Raw conservative score: -3.
* Conservative score: 0.
* Raw paranoid score: -3.
* Paranoid score: 0.
* Applied score lower bound: -3 -> 0.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Reliable kernel crash or strong DoS. An `ERR_PTR`, including `ERR_PTR(-EPROBE_DEFER)`, is passed to `clk_get_rate()`, which dereferences `clk->core` and can generate a kernel Oops. No additional availability point is awarded for the same fault.
* -2 Host-admin-equivalent control. An intentional trigger requires control over the platform-driver probe or reprobe sequence and clock-provider availability. No unprivileged interface for controlling this sequence is established.
* -2 Rare hardware requirement. The vulnerable driver is specific to the Microchip PolarFire SoC RTC and requires that platform hardware and driver configuration.
* No UAF, OOB access, heap overwrite, shared-backing write, repeated release, active-state corruption, or authorization bypass is established.
* B5-R does not apply. There is no heap OOB write, retry-accumulated index, or later consumption of corrupted structured state.
* B3-PENDING does not apply. No shared or file-backed storage is modified.
* V33 and V34 do not apply. There is no attacker-influenced active structured state, checksum metadata, or downstream privileged networking consumer.
* Confidentiality and integrity points are not awarded. The operation is an invalid pointer read that is expected to fault, not a useful disclosure or write primitive.
* No paranoid point is added merely because `panic_on_oops` could convert the same Oops into a system-wide panic.

3. Reachability analysis

The failure occurs during `mpfs_rtc_probe()` when the `rtcref` clock provider has not registered its clocks and `devm_clk_get()` returns an error pointer. It may occur naturally because of driver probe ordering, but no attacker-invocable ordinary-user or network interface is identified.

Reliable intentional reproduction would require host-level control over module loading, driver binding or reprobe, platform-device state, or clock-provider registration. These operations are not namespace scoped. The required Microchip PolarFire SoC platform is a concrete hardware prerequisite. No race is involved and no timing penalty is applied separately.

4. Primitive and severity interpretation

The exact primitive is an invalid `ERR_PTR` dereference in `clk_get_rate()`. It is CLASS_C invalid-state and crash behavior, not memory corruption or a lifetime violation. The demonstrated consequence is an RTC probe failure and kernel Oops, with a possible host panic depending on kernel configuration.

There is no useful operation remaining after excluding the fault. No memory is written through the invalid pointer, no stale object is reused, and no protected state is accessed. ImportantCandidate is therefore NO. AutoDowngradeAllowed is YES because no unresolved corruption, ownership, authorization, or trust-boundary primitive remains. Operational severity is Low-like and hardware specific.

5. One-sentence report phrase

The Microchip PolarFire SoC RTC probe can dereference an error pointer returned for an unavailable rtcref clock and cause a kernel Oops, but the issue requires specialized hardware and exposes no unprivileged, network, memory-corruption, or authorization-bypass primitive.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch establishes a direct invalid error-pointer dereference with availability impact only, and none of the B5-R, B3-PENDING, B4-PENDING, active-state, UAF, or cross-boundary preservation conditions apply.

7. Call-site confidence

Call-site confidence: high

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

Patch: rtc: mpfs: fix unchecked devm_clk_get() error pointer in probe() [ Upstream
Commit: 74dc7c52946e3d47c40edd0875adb7cc15937066
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=74dc7c52946e3d47c40edd0875adb7cc15937066

Changed files:
  drivers/rtc/rtc-mpfs.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=74dc7c52946e3d47c40edd0875adb7cc15937066

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

The original Linux kernel CVE announcement for CVE-2026-98825 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98825

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:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.1

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: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).