[CVE-2026-90428][LOW] iommu/tegra241-cmdqv: Don't run the error ISR before probe sets up vintfs [ Upstream

[CVE-2026-90428][LOW] iommu/tegra241-cmdqv: Don't run the error ISR before probe sets up vintfs [ Upstream

[AL-KERNEL]

CVE: CVE-2026-90428
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: iommu/tegra241-cmdqv: Don't run the error ISR before probe sets up vintfs [ Upstream
Commit: b1605a56745f22670205f6561df5771bbbb62a99
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b1605a56745f22670205f6561df5771bbbb62a99
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90428
Analysis date: Fri, 18 Sep 2026 04:11:13 -0400
ActionableScore: 1
ActionableScore lower bound: 0
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-2026-90428 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90428

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-2026-90428	LOW	https://www.kernelcve.org/list/?q=CVE-2026-90428 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:L/I:L/A:H';CWE-665;CWE-824;CWE-362;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.2';DESCR 'Tegra241 CMDQV probe can request the error IRQ before the vintfs array and num_vintfs are initialized. If a CMDQV remains enabled with a latched error across kexec, the IRQ can fire immediately and tegra241_cmdqv_isr can walk uninitialized pointer state. For the CVSS the PR:H is used because reliable triggering normally requires administrative control over kexec, reboot, or platform device state. The issue is not network reachable and is limited to systems using the NVIDIA Tegra241 Grace CMDQV path. Impact is primarily denial of service through a kernel crash during probe, with a paranoid LLH impact kept for manual review because interrupt handling may access uninitialized pointer state.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	YES	INIT ERRORPATH DEBUGFS LINUS 	YES	NO	checked

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

ActionableScore=1
ActionableScoreLower=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::

No floor was applied. No cap was applied. Conservative score is reduced by the positively supported host-admin-equivalent trigger requirement. Paranoid score adds one limited point for interrupt-time uninitialized pointer-state handling, but does not promote the issue to a memory-corruption or privilege-escalation candidate.

2. Signal breakdown

Conservative signals:

* +1 CLASS_C weak invalid-state primitive. The IRQ handler may walk cmdqv->vintfs before cmdqv->vintfs and cmdqv->num_vintfs are initialized.
* +1 Reliable kernel crash / strong DoS. A latched error IRQ can fire immediately after request_threaded_irq() and cause the ISR to touch invalid initialization state.
* -2 Host-admin-equivalent trigger requirement. The described trigger depends on kexec, reboot, or platform device state that is normally controlled by host administration.

Conservative total: +1 +1 -2 = 0.

Paranoid additional signal:

* +1 Limited interrupt-time uninitialized structured-state concern. The stale early ISR path walks driver-maintained pointer state before setup, so manual review is useful even though no concrete arbitrary write, UAF, or controlled reclaim is shown.

Paranoid total: +1 +1 +1 -2 = 1.

Important non-awarded signals:

* RealUAF not awarded. No freed object or post-lifetime object use is established.
* Concrete repeated release/refcount not awarded. There is no first release that may end lifetime followed by a second lifetime mutation on the same dangling reference.
* Controlled reclaim not demonstrated.
* Arbitrary or directed kernel write not demonstrated.
* Confidentiality and integrity signals not awarded. The patch supports invalid pointer-state access and crash risk, not a concrete disclosure or unauthorized modification primitive.
* Remote reachability not established.
* Namespace-scoped privilege not established.
* Extra availability not awarded because the same crash/probe failure is already counted once.
* Strong LPE or CLASS_A not awarded because there is no controlled corruption, callback control, refcount takeover, boundary bypass, or demonstrated privilege escalation.

3. Reachability analysis

The described trigger is a CMDQV left enabled with a latched error across kexec. The error IRQ fires as soon as it is requested during the next probe, before the driver has allocated and zeroed the vintfs array.

The evaluated attacker is effectively a host administrator or host-privileged actor able to control kexec, reboot, or low-level platform/device state. Ordinary local-user reachability is not established. Namespace-scoped reachability is not relevant because this is an IOMMU platform-driver probe path, not a namespace-created object or per-netns control path.

There is prior privileged setup in the practical trigger because kexec or equivalent platform state control is required. The affected path is also hardware-specific to NVIDIA Tegra241 Grace CMDQV support. I did not subtract an additional hardware penalty because the host-admin requirement already captures the main practical reachability restriction, and the rules discourage reducing severity merely because code is in a driver.

The timing condition is not scored as a hard race. If the latched interrupt exists, the early IRQ delivery is a deterministic ordering problem caused by requesting the IRQ before initialization.

4. Primitive and severity interpretation

The exact primitive is an initialization-ordering bug in an interrupt path. __tegra241_cmdqv_probe() requested the error IRQ before allocating cmdqv->vintfs and setting cmdqv->num_vintfs. If a latched device error is present, tegra241_cmdqv_isr() can run against uninitialized driver state.

This is not a UAF and not a repeated refcount/lifetime mutation. It is best classified as CLASS_C invalid-state behavior with potential kernel crash during probe. The stale state is driver initialization state, not a freed active object with established reuse or replacement leverage.

The demonstrated consequence is denial of service through kernel crash or failed probe on a specific platform path. A speculative stronger consequence would require an additional primitive such as controlled pointer contents, controlled memory corruption, or attacker-shaped replacement state, none of which is supported by the supplied patch.

ImportantCandidate=NO because the evidence supports host-admin-gated crash behavior rather than unresolved Important-grade exploitation leverage. AutoDowngradeAllowed=YES because there is no UAF, no repeated release/refcount mutation, no authorization bypass, no ownership/COW violation, and no controlled corruption primitive.

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

5. One-sentence report phrase

An initialization ordering bug in the Tegra241 CMDQV probe path can let a latched error IRQ run before the vintfs array is initialized, causing the ISR to walk invalid driver state and potentially crash the kernel during probe.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Manual review is recommended because this is interrupt-time execution against uninitialized pointer state in an IOMMU driver, but the supplied evidence points to a host-admin-gated, platform-specific DoS rather than a clear Important-class corruption primitive.

7. Call-site confidence

Call-site confidence: medium

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

Patch: iommu/tegra241-cmdqv: Don't run the error ISR before probe sets up vintfs [ Upstream
Commit: b1605a56745f22670205f6561df5771bbbb62a99
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b1605a56745f22670205f6561df5771bbbb62a99

Changed files:
  drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.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=b1605a56745f22670205f6561df5771bbbb62a99

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

The original Linux kernel CVE announcement for CVE-2026-90428 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90428

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:H/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 5.2

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: 0
  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).