[CVE-2026-74416][LOW] drm/radeon: fix memory leak in radeon_ring_restore() on lock failure [ Upstream

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

CVE: CVE-2026-74416
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/radeon: fix memory leak in radeon_ring_restore() on lock failure [ Upstream
Commit: 63912418f1fbb6456ea04bbcdf8f4d5090d23350
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=63912418f1fbb6456ea04bbcdf8f4d5090d23350
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74416
Analysis date: Sun, 16 Aug 2026 00:26:01 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A missing kvfree in radeon_ring_restore can leak the ring backup buffer when radeon_ring_lock fails during GPU reset, allowing repeated failed resets to cause cumulative kernel memory exhaustion and local DoS.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-74416 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74416

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-74416	LOW	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:L/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;**CWE-400;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A memory leak in radeon_ring_restore can occur when radeon_ring_lock fails during the GPU reset restore path. The function owns the ring backup buffer returned by radeon_ring_backup but returned early without freeing data, so repeated failed restore attempts can accumulate kernel memory leaks. For the CVSS the PR:L is used because local GPU access through DRM render or primary nodes may be available to non-root users in some deployments, although reliable triggering still depends on reset and lock failure conditions. The issue is not network reachable and does not provide a direct memory corruption primitive. Impact is denial of service through cumulative kernel memory exhaustion, not information disclosure or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)	YES	SIMPLEFIX LEAK HARDWARE 	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=2
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**::

## 2. Signal breakdown

Triggered signals:

* Local unprivileged trigger: +1. Local users may have access to DRM render or primary nodes in some deployments, but reliable triggering depends on GPU reset behavior and the radeon_ring_lock failure path.
* Availability impact realistic: +1. Repeated failed GPU reset restore attempts can leak kernel memory and may eventually cause memory exhaustion.

Subtracted signals:

* Hard or unreliable condition required: -1. The leak requires a GPU reset that reaches the restore path and then fails at radeon_ring_lock.
* Rare or configuration dependent condition: optional -1 for conservative interpretation. This depends on Radeon hardware and a specific reset failure mode, but I did not apply this in the paranoid score because DRM access can be ordinary on affected systems.

Not applied:

* No generic memory corruption. This is a missing kvfree on an error path, not UAF, OOB write, double free, or type confusion.
* No privilege escalation plausible. The patch does not show attacker controlled reuse, overwrite, callback control, or object confusion.
* No confidentiality or integrity impact. The leak affects kernel memory availability only.
* No remote reachability. This is local GPU driver behavior, not a network path.

## 3. Reachability analysis

The bug is reachable only on systems using the radeon DRM driver and only when GPU reset enters the ring restore path. A local user with GPU access may be able to contribute to GPU reset conditions, but reliable triggering of the exact lock failure is not guaranteed from the patch alone. Containers usually do not get direct DRM device access unless explicitly passed through. The path is not remotely reachable and not a common networking or filesystem path.

Call-site confidence: medium. The commit message identifies radeon_gpu_reset as the caller and explains ownership transfer, but the full reset call chain is not included in the pasted patch.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like resource exhaustion issue. The theoretical impact is cumulative kernel memory exhaustion during repeated GPU reset failures. There is no evidence of memory corruption, privilege escalation, arbitrary write, sensitive data exposure, or cross-boundary policy bypass. The practical risk is limited by hardware dependency and the need to repeatedly hit a specific error path.

## 5. One-sentence report phrase

A missing kvfree in radeon_ring_restore can leak the ring backup buffer when radeon_ring_lock fails during GPU reset, allowing repeated failed resets to cause cumulative kernel memory exhaustion and local DoS.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This is a resource leak without evidence of memory corruption, network reachability, confidentiality impact, integrity impact, or privilege escalation.

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

Patch: drm/radeon: fix memory leak in radeon_ring_restore() on lock failure [ Upstream
Commit: 63912418f1fbb6456ea04bbcdf8f4d5090d23350
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=63912418f1fbb6456ea04bbcdf8f4d5090d23350

Changed files:
  drivers/gpu/drm/radeon/radeon_ring.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=63912418f1fbb6456ea04bbcdf8f4d5090d23350

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

The original Linux kernel CVE announcement for CVE-2026-74416 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74416

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:L/UI:N/S:U/C:N/I:N/A:L
  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: 1
  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).