[CVE-2026-74422][MODERATE REGULAR] drm/rockchip: inno-hdmi: Switch to drmm_kzalloc() [ Upstream

[CVE-2026-74422][MODERATE REGULAR] drm/rockchip: inno-hdmi: Switch to drmm_kzalloc() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-74422
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/rockchip: inno-hdmi: Switch to drmm_kzalloc() [ Upstream
Commit: 195ab348af4b2bdf5988f9397059317bb68fd797
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=195ab348af4b2bdf5988f9397059317bb68fd797
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74422
Analysis date: Sun, 16 Aug 2026 02:38:15 -0400
ActionableScore: 4
ActionableScore lower bound: 3
Actionable bucket: Borderline manual review recommended. Not Strong Important candidate
Manual review required: YES

Summary:
A use-after-free in the Rockchip inno HDMI DRM teardown path can occur when DRM-managed encoder cleanup accesses an encoder embedded in a structure that was already freed by device-managed component cleanup, leading primarily to a privileged local kernel crash.

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

The original Linux kernel CVE announcement for CVE-2026-74422 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74422

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: YES

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
======================================================================

CVE-2026-74422	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	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-416;*CWE-672;*CWE-664;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.2';DESCR 'A use-after-free can occur in the Rockchip inno HDMI DRM driver because the structure that embeds the DRM encoder was allocated with devm_kzalloc() while encoder cleanup is registered as a DRM managed action. During component_unbind_all() the device managed allocation can be released before drm_dev_put() later runs drmm_encoder_alloc_release(), leaving the cleanup path with a stale encoder pointer. The most likely impact is a local denial of service during driver or device teardown, because the stale pointer can cause a kernel crash. For the CVSS the PR:H is used because reliable triggering normally requires administrative control over DRM component unbind, driver unload, or platform device teardown on affected Rockchip systems. The issue is not network reachable. Impact is primarily availability, with limited confidentiality or integrity impact only in the paranoid view because the bug class is use-after-free but the patch does not show an attacker controlled write primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended. Not Strong Important candidate (with actual score 4)  SKIP CVE-2026-74422 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	UAF HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScore=4
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 4
* Final recommended bucket: **Borderline manual review recommended. Not Strong Important candidate**

## 2. Signal breakdown

Triggered signals:

* Memory corruption, strong corruption primitive: +2
  The patch explicitly fixes a use-after-free. The DRM encoder is embedded in a structure allocated with devm_kzalloc(), but encoder cleanup is registered as a DRM managed action and can run after the devm allocation is already freed.

* Real lifetime corruption: +1
  This is a real object lifetime mismatch between component-managed resources and DRM-managed cleanup.

* Reliable kernel crash / strong DoS: +1
  The stale encoder pointer is accessed during drm_dev_put() / drmm_encoder_alloc_release(), making a kernel crash plausible during teardown.

* Privileged kernel/device-management memory corruption path: +1
  The bug is in DRM driver bind/unbind and device teardown logic, which is a trusted kernel device-management path.

Subtracted signals:

* Requires admin/root/CAP_* in typical deployments: -2 conservative
  Reliable triggering normally requires driver unload, platform device unbind, DRM component teardown, or equivalent administrative device-management control.

* Rare AND difficult-to-reach subsystem/configuration: -1 conservative
  The affected path is specific to Rockchip inno HDMI DRM hardware and teardown paths, not a broad default kernel interface.

Paranoid adjustment:

* Paranoid score uses a reduced privilege penalty of -1 instead of -2
  This accounts for environments where a reduced-privilege service, container root, or delegated device-management actor can trigger DRM or platform-device teardown without being equivalent to full host root.

Not awarded:

* No remote/network reachability.
* No local unprivileged trigger shown.
* No strong LPE plausibility. The patch shows UAF, but not attacker-controlled reclaim, object replacement, callback control, type confusion, refcount takeover, or write-after-free.
* No confidentiality or integrity impact in the conservative score.

## 3. Reachability analysis

The bug is reachable during Rockchip DRM component unbind or DRM device teardown. In normal deployments this is a local privileged path requiring root or administrative control over platform devices, driver unloading, or system shutdown/rebind flows.

Namespaces and containers usually do not make this reachable unless device-management interfaces are delegated into the container or a service account is allowed to manage platform devices. The affected hardware path is not broadly exposed and is not network-triggerable. Exploitation conditions are realistic for crash testing or faulty teardown, but there is no evidence of a practical privilege escalation primitive.

Call-site confidence: high. The commit message directly describes the failing lifetime order: component_unbind_all() frees the devm allocation before drm_dev_put() runs DRM-managed encoder cleanup.

## 4. Severity interpretation

This behaves more like a borderline Moderate memory-lifetime issue than an Important-class vulnerability. The theoretical risk is elevated because the bug class is UAF, but the realistic evidence points mainly to privileged local DoS during driver or device teardown. Without attacker-controlled reclaim or a writable stale object access, it should not be treated as a strong LPE candidate.

## 5. One-sentence report phrase

A use-after-free in the Rockchip inno HDMI DRM teardown path can occur when DRM-managed encoder cleanup accesses an encoder embedded in a structure that was already freed by device-managed component cleanup, leading primarily to a privileged local kernel crash.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED.
YES REQUIRES MANUAL CHECK.

Reason: explicit UAF class bug in a kernel driver lifetime path, but current evidence supports mainly privileged local DoS rather than practical privilege escalation.

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

Patch: drm/rockchip: inno-hdmi: Switch to drmm_kzalloc() [ Upstream
Commit: 195ab348af4b2bdf5988f9397059317bb68fd797
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=195ab348af4b2bdf5988f9397059317bb68fd797

Changed files:
  drivers/gpu/drm/rockchip/inno_hdmi-rockchip.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=195ab348af4b2bdf5988f9397059317bb68fd797

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

The original Linux kernel CVE announcement for CVE-2026-74422 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74422

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: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: 3
  Paranoid ActionableScore: 4

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).