[CVE-2026-98564][MODERATE REGULAR] net: dsa: mt7530: leave the MDIO IRQ mappings to regmap-irq [ Upstream

[CVE-2026-98564][MODERATE REGULAR] net: dsa: mt7530: leave the MDIO IRQ mappings to regmap-irq [ Upstream

[AL-KERNEL]

CVE: CVE-2026-98564
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: net: dsa: mt7530: leave the MDIO IRQ mappings to regmap-irq [ Upstream
Commit: 2357c682f6eaf639dec88c68b3c0c93a3b802635
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2357c682f6eaf639dec88c68b3c0c93a3b802635
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98564
Analysis date: Mon, 19 Oct 2026 06:33:18 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
A host administrator removing an MT7530 DSA device can race a late regmap interrupt with premature PHY IRQ mapping disposal, causing an unchecked NULL descriptor dereference and kernel denial of service.

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

The original Linux kernel CVE announcement for CVE-2026-98564 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98564

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.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-98564	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98564 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=0 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:L/UI:N/S:U/C:N/I:N/A:H';CWE-362;**CWE-476;*CWE-664;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 teardown race in the mt7530 DSA driver can remove per PHY IRQ mappings while the devm managed regmap IRQ chip and its parent interrupt are still active. A late hardware interrupt can then make irq_find_mapping return zero and irq_to_desc return NULL, after which handle_nested_irq dereferences the missing descriptor and can crash the kernel. For the CVSS the PR:L value is used in the paranoid score because device lifecycle control may be delegated to a restricted service, container root, or local operator without full host administration. The realistic base case requires administrative device removal and therefore uses PR:H. AC:H applies because the interrupt must arrive during a narrow teardown window. The issue is not directly network reachable because ordinary packet delivery alone does not initiate the vulnerable removal sequence. Impact is denial of service through a kernel crash, with no supported UAF, out of bounds access, information leak, or write primitive. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 4.7 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_CIANNH 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 4.1 and ActionableScore 0 with primitive class CLASS_C and manual review RECOMMENDED. 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	INIT UAF NETWORK LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 V39_AEGIS_ONE_STEP_UP MANUAL_REVIEW_REQUIRED	-	-	checked

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

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: -2
* Conservative score: 0
* Raw paranoid score: -2
* Paranoid score: 0
* Applied score lower bound: -2 -> 0
* Final recommended bucket: **Ordinary Moderate**::

## 2. Signal breakdown

Positive signals:

* +1 Reliable kernel crash. A late regmap IRQ dispatch resolves the removed mapping to IRQ 0, obtains a NULL descriptor, and reaches an unchecked `desc->lock` access in `handle_nested_irq()`.

Negative signals:

* -2 Host-admin-equivalent operation. An attacker-driven call to the device `.remove` path requires control over host-owned driver or device lifecycle operations. No complete delegated or namespace-scoped removal path is established.
* -1 Hard one-shot teardown race. The parent interrupt must arrive after the driver prematurely disposes the PHY mappings but before devm cleanup disables the parent regmap interrupt.

Material signals not awarded:

* No UAF point. The lookup returns no mapping and produces NULL rather than retaining and dereferencing a stale descriptor.
* No corruption point. There is no OOB access, write primitive, refcount mutation, controlled replacement, or attacker-influenced active-state corruption.
* No extra availability point. It would double-count the same kernel fault.
* No C or I signal. The demonstrated behavior is an unchecked NULL dereference.
* No remote-reachability signal. Network traffic alone is not shown to initiate device removal or reliably control the teardown interrupt window.
* No namespace or delegated-privilege signal. The physical DSA switch and its driver lifecycle remain host-owned in the supplied evidence.
* V32, V33, B3-PENDING, B4-PENDING, and B5-R do not apply. There is no skb metadata write, shared-backing write, authorization decision, retry-accumulated OOB write, or cross-boundary active-state corruption.

## 3. Reachability analysis

The vulnerable sequence begins in `mt7530_remove_common()`. An attacker would need to initiate removal or unbinding of the host-owned MT7530 switch while a late hardware interrupt remains possible. Software-driven device unbind or module removal is a host-administration operation and is not established as available through a user namespace, network namespace, container capability, or delegated interface.

The switch hardware and enabled IRQ configuration are prerequisites. Ordinary packet delivery may contribute device activity, but the supplied call chain does not show that packets can initiate the required `.remove` operation or reliably schedule the interrupt inside the vulnerable window.

The race is narrow and tied to a one-time teardown transition. Repeated attempts require repeated host-level device lifecycle operations. Numeric host UID 0 is not strictly established because host administration may be represented by capabilities or kernel-managed removal, so `RequiresHostUID0` remains UNKNOWN.

## 4. Primitive and severity interpretation

The exact primitive is an unchecked NULL descriptor dereference during IRQ-domain teardown. It is not a real UAF because the removed mapping is looked up again and produces IRQ 0 and then NULL, rather than returning a stale descriptor.

This is a teardown-only Class C condition. There is no repeated release, second refcount mutation, active structured stale-object consumption, or meaningful behavior after memory reuse. The demonstrated consequence is a kernel fault and host denial of service. Stronger consequences such as disclosure, arbitrary write, privilege escalation, or active-state corruption are unsupported.

`ImportantCandidate=NO` because the patch establishes only a privileged, timing-dependent crash path. `AutoDowngradeAllowed=YES` because no unresolved corruption, ownership, authorization, or trust-boundary primitive remains.

## 5. One-sentence report phrase

A host administrator removing an MT7530 DSA device can race a late regmap interrupt with premature PHY IRQ mapping disposal, causing an unchecked NULL descriptor dereference and kernel denial of service.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

The complete supplied chain is a host-admin-controlled, narrow teardown race with a deterministic NULL dereference and no evidence of UAF, memory corruption, authorization bypass, or below-host-admin reachability.

## 7. Call-site confidence

Call-site confidence: high

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

Patch: net: dsa: mt7530: leave the MDIO IRQ mappings to regmap-irq [ Upstream
Commit: 2357c682f6eaf639dec88c68b3c0c93a3b802635
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2357c682f6eaf639dec88c68b3c0c93a3b802635

Changed files:
  drivers/net/dsa/mt7530.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=2357c682f6eaf639dec88c68b3c0c93a3b802635

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

The original Linux kernel CVE announcement for CVE-2026-98564 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98564

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: 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).