[CVE-2026-80870][LOW] drm/amdkfd: Validate CRIU-restored IDs before idr_alloc [ Upstream

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

CVE: CVE-2026-80870
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amdkfd: Validate CRIU-restored IDs before idr_alloc [ Upstream
Commit: f8687018f24037056692c1e93c7d96cc72889d5b
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f8687018f24037056692c1e93c7d96cc72889d5b
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80870
Analysis date: Fri, 04 Sep 2026 18:17:50 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-80870 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80870

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.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-80870	LOW	https://www.kernelcve.org/list/?q=CVE-2026-80870 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:N/I:N/A:H';*CWE-20;CWE-617;CWE-754;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'amdkfd CRIU restore accepts restored event and BO identifiers from userspace and could pass values larger than INT_MAX into idr_alloc. This can trigger a kernel WARN in the IDR layer and may become a local denial of service on systems where panic_on_warn converts WARN into panic or reboot. For the CVSS the PR:L is selected because triggering requires a local user or process with access to the amdkfd CRIU restore path and the related GPU device interface, but not full administrator privileges in typical delegated GPU environments. The issue is not network reachable and does not provide a demonstrated memory corruption primitive. Impact is mainly availability loss via WARN or panic_on_warn, with no supported confidentiality or integrity impact from this patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)  SKIP CVE-2026-80870 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	INIT WARNONLY HARDWARE BOOT  INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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

ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 2
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate**::

No floor or cap changed the score.

2. Signal breakdown

Conservative signals:

* +1 Local below-host-admin trigger: the KFD CRIU restore path accepts userspace-provided restored IDs through the amdkfd device interface. This is local and requires access to the relevant GPU/KFD interface, but host-admin-equivalent privilege is not established.
* +0 WARN-only invalid input: the direct demonstrated consequence is an IDR-layer WARN from an out-of-range restored ID. WARN alone is not counted as a reliable crash in the conservative score.

Paranoid signals:

* +1 Local below-host-admin trigger: same as conservative.
* +1 Strong DoS on panic_on_warn systems: the commit explicitly states that WARN may cause panic or reboot when panic_on_warn is enabled.

Non-awarded signals:

* No UAF is established.
* No OOB access is established.
* No double release or repeated refcount mutation is established.
* No controlled reclaim is demonstrated.
* No arbitrary or directed kernel write is demonstrated.
* No confidentiality or integrity impact is awarded because the patch shows invalid input reaching idr_alloc and causing WARN, not data disclosure or unauthorized modification.
* No extra availability point is awarded beyond the paranoid panic_on_warn consequence.
* No remote reachability is established.
* No Important-grade security-boundary bypass is established.

3. Reachability analysis

The trigger is local through the amdkfd CRIU restore flow. The attacker must provide crafted restore data containing event_id or idr_handle values larger than INT_MAX. The relevant actor is a local process with access to the KFD device and CRIU restore operation. Full host administrator privilege is not positively established, so HostAdminRequired is NO.

NamespaceScopedPrivilege is UNKNOWN because the supplied evidence does not establish that the complete KFD CRIU restore operation is namespace-scoped or attacker-obtainable through namespaces.

There is no network path. There is no race requirement. The issue depends on AMD KFD functionality and relevant GPU/KFD device availability, but common GPU hardware is not treated as rare hardware by itself.

4. Primitive and severity interpretation

The exact primitive is unchecked userspace integer input passed into idr_alloc with an ID value above INT_MAX. This is an input-validation failure leading to an invalid IDR-layer state check and WARN.

PrimitiveClass is CLASS_C because the demonstrated behavior is WARN or possible panic_on_warn DoS without an independently useful corruption, lifetime, ownership, or authorization primitive.

RealUAF is NO. There is no active structured stale object, no fixed stale storage, no cleanup UAF, and no concrete repeated release or refcount operation.

The demonstrated consequence is local availability impact through WARN, with possible host panic or reboot only on systems configured with panic_on_warn. The speculative consequence does not extend to privilege escalation or memory corruption based on the supplied patch and context.

ImportantCandidate is NO because there is no Class A primitive and no strong Class B unresolved lifetime or corruption primitive. AutoDowngradeAllowed is YES because this is a validation-only WARN or panic_on_warn DoS case without memory corruption, security-boundary bypass, or unresolved exploitation leverage.

Likely operational severity is Low to ordinary Moderate.

5. One-sentence report phrase

amdkfd CRIU restore accepted userspace supplied event and BO IDs above INT_MAX, allowing a local KFD user to trigger an IDR WARN and potentially a panic_on_warn denial of service.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: this is a local input-validation issue with WARN or panic_on_warn availability impact only, and the patch does not establish UAF, memory corruption, privilege escalation, information disclosure, or a security-boundary bypass.

7. Call-site confidence

Call-site confidence: high

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

Patch: drm/amdkfd: Validate CRIU-restored IDs before idr_alloc [ Upstream
Commit: f8687018f24037056692c1e93c7d96cc72889d5b
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f8687018f24037056692c1e93c7d96cc72889d5b

Changed files:
  drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
  drivers/gpu/drm/amd/amdkfd/kfd_events.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=f8687018f24037056692c1e93c7d96cc72889d5b

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

The original Linux kernel CVE announcement for CVE-2026-80870 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80870

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:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

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: 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).