[CVE-2026-68258][MODERATE 7.0] drm/amdkfd: Check bounds on CRIU restore queue type and mqd size

[CVE-2026-68258][MODERATE 7.0] drm/amdkfd: Check bounds on CRIU restore queue type and mqd size

[AL-KERNEL]

CVE: CVE-2026-68258
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/amdkfd: Check bounds on CRIU restore queue type and mqd size
Commit: fd1691ec62701c982ea32e749678988c67fd4c21
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fd1691ec62701c982ea32e749678988c67fd4c21
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68258
Analysis date: Mon, 10 Aug 2026 14:13:40 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A malformed amdkfd CRIU restore payload can supply an out-of-range queue type or mismatched MQD size, potentially causing invalid GPU queue metadata parsing and local kernel or driver crash, with weak but review-worthy concern for memory corruption in the restore path.

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

The original Linux kernel CVE announcement for CVE-2026-68258 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68258

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 7.0
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
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CVE-2026-68258	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-20;CWE-129;CWE-130;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7.8';DESCR 'A malformed amdkfd CRIU restore payload can provide an out of range queue type or an MQD size that does not match the expected size for that queue type. These fields are used while restoring GPU queue state and parsing the private restore data, so invalid values can drive the kernel into an inconsistent queue restore path and may cause invalid memory access or memory corruption. For the CVSS the PR:L is used because triggering requires a local process with access to the AMD KFD restore interface or equivalent delegated GPU checkpoint restore capability. The issue is not network reachable and cannot be triggered by remote packets. Impact is at least local denial of service via driver or kernel crash. In the worst case it may allow confidentiality and integrity impact due to a user controlled restore structure influencing kernel queue metadata, so manual review is recommended.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 5)	MAYBE	INIT HARDWARE  INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP	-	-	guess

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

ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged or low-privileged trigger: +1
  The vulnerable path is a local amdkfd CRIU restore path. It is not network reachable, but may be reachable by a local process with access to the AMD KFD device or delegated GPU checkpoint restore functionality.

* Memory corruption, weak or indirect corruption candidate: +1
  The patch validates a user-controlled queue type and mqd_size. Before the fix, an out-of-range queue type could affect queue-type-to-MQD-manager selection, and an invalid mqd_size could desynchronize parsing of the restore private data layout.

* Privileged kernel/device-management corruption path: +1
  The affected code restores GPU queue metadata inside the amdkfd kernel driver. The objects are trusted device-management structures, even though the patch does not prove a strong attacker-controlled overwrite primitive.

* Availability impact realistic: +1
  Malformed restore data can plausibly drive invalid queue parsing or invalid object access, making local driver or kernel crash a realistic impact.

Paranoid additional signal:

* Weak LPE concern: +1
  The restored queue metadata is influenced by user-provided CRIU private data and later used in kernel GPU queue setup. This is not a demonstrated LPE primitive, but it is enough to require manual source review for possible corruption sinks.

Caps and non-applied signals:

* No remote reachable signal. The path is local only.
* No strong generic memory corruption signal. The patch is validation-oriented and does not show UAF, double free, OOB write, arbitrary write, or controlled reclaim.
* No high-control device API bonus. Object configuration through a GPU ioctl is not enough by itself under the RDMA/device-object API rule.
* Conservative score is kept at 4 and paranoid score at 5 due to the validation-only unspecified-corruption cap.

## 3. Reachability analysis

A local process must reach the amdkfd CRIU restore queue path and provide malformed private restore data. This generally requires access to AMD KFD device functionality and a system with amdgpu/amdkfd enabled. It does not require packet-level or remote network access.

Namespaces and containers may matter if `/dev/kfd` or GPU device nodes are passed into a container or delegated to a service account. In that model, the attacker may not be full host root, so treating this as PR:L is more appropriate than PR:H for practical triage. In a locked-down deployment without user access to KFD or CRIU restore operations, reachability is much lower.

Call-site confidence: medium. The patch shows the validation site and the affected restore parsing flow, but not all downstream consumers of the restored MQD and queue metadata.

## 4. Severity interpretation

This is more than an ordinary low-risk validation cleanup because user-controlled queue type and mqd_size values influence kernel GPU queue restore state. However, the patch does not demonstrate a concrete arbitrary write, UAF, type confusion, or reclaim primitive. Realistic evidence supports local DoS or driver/kernel state corruption. The paranoid interpretation supports Actionable Moderate handling because the affected objects are GPU queue metadata in a trusted kernel driver and deserve manual review for possible LPE sinks.

## 5. One-sentence report phrase

A malformed amdkfd CRIU restore payload can supply an out-of-range queue type or mismatched MQD size, potentially causing invalid GPU queue metadata parsing and local kernel or driver crash, with weak but review-worthy concern for memory corruption in the restore path.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Manual review is required because the bug involves user-controlled restore metadata used to reconstruct kernel GPU queue state. The current patch supports a weak corruption candidate rather than a proven exploit primitive, but the affected path is sensitive enough that it should not be auto-closed.

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

Patch: drm/amdkfd: Check bounds on CRIU restore queue type and mqd size
Commit: fd1691ec62701c982ea32e749678988c67fd4c21
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fd1691ec62701c982ea32e749678988c67fd4c21

Commit description:

We weren't checking whether the values provided in the private
data in kfd CRIU restore were within bounds.

For queue type, add a KFD_QUEUE_TYPE_MAX and ensure the provided
type is less than it.

For mqd_size, add new function mqd_size_from_queue_type and confirm
that the provided mqd_size matches expectations.

Reviewed-by: David Yat Sin <david.yatsin@amd.com>
Signed-off-by: David Francis <David.Francis@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit f19d808 )
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
  drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h
  drivers/gpu/drm/amd/amdkfd/kfd_priv.h
  drivers/gpu/drm/amd/amdkfd/kfd_process_queue_manager.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=fd1691ec62701c982ea32e749678988c67fd4c21

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

The original Linux kernel CVE announcement for CVE-2026-68258 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68258

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:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 4
  Paranoid ActionableScore: 5

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 7.0

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).