[CVE-2026-64039][LOW] drm/msm/snapshot: fix dumping of the unaligned regions [ Upstream

[CVE-2026-64039][LOW] drm/msm/snapshot: fix dumping of the unaligned regions [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64039
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/msm/snapshot: fix dumping of the unaligned regions [ Upstream
Commit: 8fb070cf95847b29ef6cb15ec2c0de2bf4704676
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8fb070cf95847b29ef6cb15ec2c0de2bf4704676
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64039
Analysis date: Sun, 19 Jul 2026 17:12:35 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
The MSM DRM snapshot code used incorrect length accounting for unaligned register regions, causing inaccurate dumps and about 16x memory over-allocation in a local diagnostic or recovery path, with impact limited to low-confidence local DoS.

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

The original Linux kernel CVE announcement for CVE-2026-64039 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64039

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-2026-64039	LOW	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:L/UI:N/S:U/C:N/I:N/A:L';CWE-682;CWE-131;**CWE-400;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '2.5';DESCR 'The drm msm snapshot code used incorrect length accounting for register dump regions and could allocate about 16x more memory than needed while also producing inaccurate dumps for unaligned DSI regions. This is a local diagnostic or recovery path issue rather than a packet or remote attack surface. For the CVSS the PR:L is used for the paranoid score because a local unprivileged graphics client may be able to trigger display snapshot paths indirectly through driver error or recovery handling, although direct debugfs snapshot control is usually privileged. The issue is not network reachable. Impact is limited denial of service from unnecessary memory consumption or failed snapshot handling, with no supported path to privilege escalation or arbitrary memory corruption.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)  SKIP CVE-2026-64039 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	DANGER SIMPLEFIX HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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

ActionableScore=1
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Conservative signals:

* Requires admin/root or debug/recovery control in typical deployments: -2. Direct triggering of MSM display snapshot/debug paths is usually privileged or device/recovery specific.
* Rare AND difficult-to-reach subsystem/configuration: -1. This is Qualcomm MSM DRM snapshot code, not a broad default kernel path.
* Availability impact realistic: +1. The 16x over-allocation can cause failed allocations or local resource pressure in the snapshot path, but the patch does not show a reliable system-wide crash.
* No generic memory corruption: +0. The patch fixes incorrect size accounting and over-allocation, not UAF, double-free, OOB write, type confusion, or arbitrary write.
* No confidentiality or integrity impact: +0. The diff does not show data disclosure or modification of protected data.

Paranoid additional signal:

* Local unprivileged indirect trigger: +1. A local graphics client might indirectly contribute to display error or recovery paths that take snapshots, although this is not demonstrated and direct snapshot controls are normally privileged.

## 3. Reachability analysis

The affected path is local and device-specific. It is not network reachable. Realistic triggering requires an MSM DRM device and a display snapshot path, usually through debug, diagnostic, crashdump, or recovery handling. In typical deployments this is not an ordinary unprivileged interface, although a local graphics workload could possibly influence display recovery indirectly. Namespaces or containers do not clearly lower the privilege requirement unless the product exposes DRM device access and recovery behavior to sandboxed workloads.

Call-site confidence: medium. The patch includes the changed snapshot helper and its direct caller, but not all external paths that initiate snapshot collection.

## 4. Severity interpretation

This behaves like a Low or ordinary Moderate issue, not an Actionable Moderate or Important candidate. The main issue is incorrect length accounting causing inaccurate dumps and excessive allocation. Theoretical impact is limited to local availability degradation from memory over-allocation or failed snapshot handling. There is no realistic evidence of privilege escalation, memory corruption, attacker-controlled overwrite, sensitive disclosure, or cross-boundary policy bypass.

## 5. One-sentence report phrase

The MSM DRM snapshot code used incorrect length accounting for unaligned register regions, causing inaccurate dumps and about 16x memory over-allocation in a local diagnostic or recovery path, with impact limited to low-confidence local DoS.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed or deferred in most triage workflows because it is a device-specific diagnostic path with no demonstrated memory corruption, no network reachability, no privilege escalation primitive, and only limited availability impact.

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

Patch: drm/msm/snapshot: fix dumping of the unaligned regions [ Upstream
Commit: 8fb070cf95847b29ef6cb15ec2c0de2bf4704676
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8fb070cf95847b29ef6cb15ec2c0de2bf4704676

Changed files:
  drivers/gpu/drm/msm/disp/msm_disp_snapshot_util.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=8fb070cf95847b29ef6cb15ec2c0de2bf4704676

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

The original Linux kernel CVE announcement for CVE-2026-64039 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64039

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:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS score: 2.5

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).