[CVE-2026-93072][LOW] irqchip/renesas-irqc: Fix generic interrupt chip leak on remove [ Upstream

[CVE-2026-93072][LOW] irqchip/renesas-irqc: Fix generic interrupt chip leak on remove [ Upstream

[AL-KERNEL]

CVE: CVE-2026-93072
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: irqchip/renesas-irqc: Fix generic interrupt chip leak on remove [ Upstream
Commit: 3d39757ef791f90028da9c8b7c1fbbb497237e58
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3d39757ef791f90028da9c8b7c1fbbb497237e58
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93072
Analysis date: Fri, 18 Sep 2026 08:20:20 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
The Renesas IRQC driver failed to destroy irq domain generic chips on driver removal, leaving stale global list entries that may be accessed during suspend, resume, or shutdown and cause a host-admin-triggered kernel crash.

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

The original Linux kernel CVE announcement for CVE-2026-93072 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93072

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-2026-93072	LOW	https://www.kernelcve.org/list/?q=CVE-2026-93072 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H';*CWE-401;*CWE-416;*CWE-772;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.4';DESCR 'The Renesas IRQC driver can leak irq domain generic chip objects during driver removal because the domain does not request automatic generic chip destruction. The leaked generic chips can remain on a global list after the driver is removed and can later be reached by generic interrupt chip suspend, resume, or shutdown callbacks. This creates a use after free candidate and can cause a kernel crash. For the CVSS the PR:H is selected because reliable triggering normally requires administrative control over platform driver removal or device unbind on the victim. The issue is not network reachable and is tied to local driver lifecycle and power management paths on systems using this irqchip. Impact is at least local denial of service. In the paranoid interpretation, stale generic chip list entries may allow confidentiality or integrity impact due to use after free behavior, so manual review is recommended.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	YES	LEAK ERRORPATH UAF KERNEL_PANIC_PLUS_UAF LINUS 	NO	NO	checked

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

ActionableScore=2
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

## 1. ActionableScore

* Raw conservative score: 2
* Conservative score: 2
* Raw paranoid score: 2
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate**::

No floor or cap changed the score. Real UAF is present, but the complete trigger appears tied to host-admin-level driver lifecycle operations and no meaningful exploitation primitive beyond crash is established.

## 2. Signal breakdown

Positive signals:

* +2 Real UAF / lifetime violation. Generic interrupt chips remain on a global list after driver removal and may later be accessed by suspend, resume, or shutdown callbacks after the driver state is gone.
* +1 Concrete persistent kernel resource/reference leak. The patch directly establishes missing automatic destruction of irq domain generic chips.
* +1 Reliable kernel crash / strong DoS. The commit states that later callback access can result in use-after-free and kernel crash.

Negative signals:

* -2 Host-admin-equivalent requirement. The relevant operation is driver removal or device unbind plus later system suspend, resume, or shutdown style callbacks, which are host administrative lifecycle operations.

Important non-awarded signals:

* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* Confidentiality and integrity impact not awarded because the patch supports stale access and crash, not a concrete disclosure or modification primitive.
* Structured stale-object leverage not awarded because there is no evidence of attacker-shaped replacement contents or useful stale field consumption beyond callback-time crash risk.
* Weak LPE not awarded merely because UAF is mentioned.
* Extra Availability not awarded because the same kernel crash is already counted.
* Concrete repeated release/refcount signal not awarded. The patch does not show first release of an exact object followed by a second lifetime-mutating release on the same dangling reference.
* FLOOR 5 not applied because the issue is host-admin-gated and does not show repeated refcount mutation, controlled reuse, or below-host-admin exploitation surface.

## 3. Reachability analysis

The trigger is local and tied to the lifecycle of the Renesas IRQC platform driver and its interrupt domain. A realistic trigger requires removal or unbind of the driver or device, followed by generic interrupt chip suspend, resume, or shutdown callback activity. This is not network reachable.

HostAdminRequired is YES because the complete driver removal and platform-device lifecycle control is host-admin-equivalent in normal kernel deployments. NamespaceScopedPrivilege is NO because this irqchip driver is not a namespace-scoped object and the operation is not reachable through an attacker-created user or network namespace.

Prior host setup exists in the sense that the affected Renesas IRQC hardware or platform device must be present and the driver must be active. This is hardware-specific, but no additional rare-hardware penalty was applied because the host-admin privilege requirement already captures the main reachability restriction. No attacker-repeatable race is established.

## 4. Primitive and severity interpretation

The exact primitive is a resource and lifetime cleanup bug. The driver allocates irq domain generic chips, but without IRQ_DOMAIN_FLAG_DESTROY_GC those generic chips are not destroyed when irq_domain_remove() is called. The leaked chips can remain on a global list and can later be reached by generic interrupt chip power-management or shutdown callbacks.

This is an active structured-object lifetime issue, not fixed stale storage. However, the demonstrated consequence is a stale post-driver-removal access leading to kernel crash. The supplied evidence does not establish controlled reclaim, attacker-controlled replacement, callback pointer hijack, arbitrary read/write, sensitive disclosure, or privilege escalation.

PrimitiveClass is CLASS_B because a real lifetime/UAF primitive is directly implied. It is not CLASS_A because no strong exploitation primitive is established. ImportantCandidate is NO because the issue is constrained by host-admin driver lifecycle control and currently supports DoS rather than unresolved below-host-admin exploitation leverage. AutoDowngradeAllowed is YES because this appears to be a constrained host-admin-gated cleanup/lifecycle UAF with crash-only demonstrated impact and no concrete repeated refcount mutation.

Likely operational severity is ordinary Moderate or Low-like for security triage, despite being a real kernel correctness bug.

## 5. One-sentence report phrase

The Renesas IRQC driver failed to destroy irq domain generic chips on driver removal, leaving stale global list entries that may be accessed during suspend, resume, or shutdown and cause a host-admin-triggered kernel crash.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

A real UAF/lifetime issue is directly implied, but the trigger appears host-admin-gated and no exploitation leverage beyond crash is established.

## 7. Call-site confidence

Call-site confidence: medium

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

Patch: irqchip/renesas-irqc: Fix generic interrupt chip leak on remove [ Upstream
Commit: 3d39757ef791f90028da9c8b7c1fbbb497237e58
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3d39757ef791f90028da9c8b7c1fbbb497237e58

Changed files:
  drivers/irqchip/irq-renesas-irqc.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=3d39757ef791f90028da9c8b7c1fbbb497237e58

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

The original Linux kernel CVE announcement for CVE-2026-93072 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93072

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:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.4

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: 2

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).