[CVE-2026-72386][LOW] drm/panthor: Fix a leak when a group is evicted before the tiler OOM is serviced [ Upstream

[CVE-2026-72386][LOW] drm/panthor: Fix a leak when a group is evicted before the tiler OOM is serviced [ Upstream

[AL-KERNEL]

CVE: CVE-2026-72386
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/panthor: Fix a leak when a group is evicted before the tiler OOM is serviced [ Upstream
Commit: 490fe7d00fcdac2dd0c204b0007f3a945a09f918
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=490fe7d00fcdac2dd0c204b0007f3a945a09f918
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72386
Analysis date: Sun, 16 Aug 2026 01:34:16 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A local reference leak in drm/panthor can occur when pending tiler OOM work is cancelled during group eviction without dropping the associated group reference, potentially causing resource exhaustion on systems exposing the Panthor GPU device.

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

The original Linux kernel CVE announcement for CVE-2026-72386 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72386

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

CVE-2026-72386	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-772;*CWE-401;CWE-404;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 reference leak in drm panthor can occur when a group is evicted while tiler_oom_work is still pending. The pending work owns a group reference, but group_unbind_locked cancelled the work without dropping that reference when the cancellation succeeded. A local process with access to the Panthor DRM device could potentially repeat GPU workloads that create tiler OOM events and group eviction to accumulate leaked group references and cause resource exhaustion. For the CVSS the PR:L is used for the paranoid score because render nodes or GPU device access can be available to non root local users in desktop or containerized GPU workloads. The issue is not network reachable. Impact is denial of service through resource leakage rather than memory corruption or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)  SKIP CVE-2026-72386 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	SIMPLEFIX LEAK HARDWARE 	-	-	checked

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

ActionableScore=2

## 1. ActionableScore

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

## 2. Signal breakdown

Triggered signals:

* **Local unprivileged trigger: +1**
  A local process with access to the Panthor DRM device or render node may be able to exercise GPU workloads and scheduling paths.

* **Real lifetime corruption / refcount lifetime bug: +1**
  The bug is a missing `group_put()` when `cancel_work()` successfully cancels pending `tiler_oom_work`. This leaks a reference tied to the pending work item.

* **Availability impact realistic: +1**
  Repeated triggering could accumulate leaked group references and associated resources, causing local resource exhaustion.

Subtracting signals:

* **Hard or unreliable race / special timing required: -1**
  Triggering requires a specific window: group eviction before the pending tiler OOM work is serviced and successful cancellation of that work.

Not awarded:

* **No generic memory corruption**
  This is a reference leak, not UAF, double-free, OOB write, type confusion, or arbitrary write.

* **No privilege escalation plausible**
  The patch shows an object lifetime leak in the safe direction, keeping the group alive too long rather than freeing it too early.

* **No remote/network reachability**
  The affected path is local GPU driver scheduling logic.

## 3. Reachability analysis

The bug is reachable only from local GPU usage paths. On systems exposing Panthor render nodes to ordinary users, PR can reasonably be treated as local low privilege. Containers with delegated GPU access may also reach the path if the device node is passed through. The issue is not network-triggerable and depends on affected Panthor hardware and driver availability. Exploitation conditions are specific because the leak requires pending `tiler_oom_work` plus group eviction before the work is serviced.

Call-site confidence: **medium**. The patch shows the immediate lifetime rule around `cancel_work()` and `group_put()`, but broader caller context is not fully included.

## 4. Severity interpretation

This behaves like an **ordinary Moderate / Low-like resource leak**, not an Important-class kernel vulnerability. The theoretical worst case is local resource exhaustion through repeated leakage of group references. There is no supported evidence of UAF, attacker-controlled reclaim, write-after-free, object replacement, callback corruption, or privilege escalation.

## 5. One-sentence report phrase

A local reference leak in drm/panthor can occur when pending tiler OOM work is cancelled during group eviction without dropping the associated group reference, potentially causing resource exhaustion on systems exposing the Panthor GPU device.

## 6. Manual review recommendation

**NO MANUAL CHECK NEEDED**

This is a local resource leak without evidence of memory corruption, privilege escalation, sensitive data exposure, or network reachability.

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

Patch: drm/panthor: Fix a leak when a group is evicted before the tiler OOM is serviced [ Upstream
Commit: 490fe7d00fcdac2dd0c204b0007f3a945a09f918
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=490fe7d00fcdac2dd0c204b0007f3a945a09f918

Changed files:
  drivers/gpu/drm/panthor/panthor_sched.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=490fe7d00fcdac2dd0c204b0007f3a945a09f918

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

The original Linux kernel CVE announcement for CVE-2026-72386 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72386

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: 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).