[CVE-2026-90130][LOW] vdpa_sim: fix cleanup after worker creation failure [ Upstream

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

CVE: CVE-2026-90130
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: vdpa_sim: fix cleanup after worker creation failure [ Upstream
Commit: feafa109f031ed111f7f968e447c13985db498e0
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=feafa109f031ed111f7f968e447c13985db498e0
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90130
Analysis date: Thu, 17 Sep 2026 19:17:28 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
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-2026-90130 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90130

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-2026-90130	LOW	https://www.kernelcve.org/list/?q=CVE-2026-90130 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-703;CWE-754;**CWE-476;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'vdpa_sim cleanup can dereference an ERR_PTR stored in vdpasim worker if kthread_run_worker() fails during simulator creation. The failing creation path drops the device reference and reaches the common release function, where kthread_destroy_worker() was called without verifying that the worker was successfully initialized. For the CVSS the PR:L is used in the paranoid score because a reduced capability admin, container root, or service account with delegated vDPA management could create simulator devices, while typical host deployments still require administrative control. The issue is not network reachable and normally requires a local control plane operation plus a worker creation failure. Impact is denial of service via kernel general protection fault, with no supported path to information disclosure or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	YES	ERRORPATH HARDWARE LINUS 	YES	NO	checked

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

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

1. ActionableScore

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

No floor or cap was applied.

2. Signal breakdown

Positive signals:

* +1 Reliable kernel crash / strong DoS: `vdpasim_free()` can pass an `ERR_PTR` worker value to `kthread_destroy_worker()`, causing an invalid dereference and general protection fault.

Negative signals:

* No host-admin penalty applied: vDPA simulator creation is normally a privileged control-plane operation, but the supplied evidence does not fully resolve the exact complete privilege boundary.
* No race penalty applied: this is an ordered initialization failure and cleanup bug, not a timing race.
* No rare hardware penalty applied: `vdpa_sim` is a simulator, not a physical rare-device dependency.

Non-awarded signals:

* Real UAF not awarded: the supplied mechanics show an `ERR_PTR` dereference, not use of an object after its lifetime ended.
* Concrete repeated release/refcount not awarded: there is no second `put`, `release`, `kref_put`, or refcount mutation through the same potentially freed reference.
* Structured stale-object leverage not awarded: the stale operation is cleanup-time invalid pointer consumption and immediate fault behavior.
* Strong LPE or weak LPE concern not awarded: no controlled reclaim, object replacement, arbitrary write, callback control, refcount takeover, or privilege boundary bypass is established.
* Confidentiality and integrity not awarded: no disclosure or unauthorized state modification primitive is shown.
* Extra availability not awarded: the same GPF/crash is already counted once.

3. Reachability analysis

The vulnerable path is reached when creating a `vdpa_sim` instance and `kthread_run_worker()` fails. The cleanup path then releases the partially initialized simulator and reaches `vdpasim_free()`.

The likely attacker is a local control-plane actor able to create or manage vDPA simulator devices. Ordinary unprivileged reachability is not established. Host-admin-equivalent privilege is plausible in normal deployments, but the supplied evidence does not prove the exact capability namespace or all required privilege checks, so `HostAdminRequired=UNKNOWN` and `NamespaceScopedPrivilege=UNKNOWN`.

There is no network trigger. There is no guest-to-host path shown. The trigger also depends on worker creation failure, which is an error condition, but not a race.

4. Primitive and severity interpretation

The exact primitive is an invalid `ERR_PTR` dereference during cleanup of a partially initialized `vdpa_sim` object. This is not an active structured UAF and not fixed stale storage. It is a cleanup/destructor-path invalid pointer use with demonstrated consequence of a kernel general protection fault.

Primitive class is `CLASS_C`: crash/DoS behavior without an independently useful corruption or lifetime primitive.

ImportantCandidate is `NO` because the patch supports only crash behavior and does not establish UAF, repeated lifetime mutation, controlled memory corruption, authorization bypass, or privilege escalation. AutoDowngradeAllowed is `YES` because no unresolved Important-grade primitive remains.

Likely operational severity is ordinary Moderate/Low-like: local, control-plane dependent, error-path dependent, and DoS-only.

5. One-sentence report phrase

`vdpa_sim` cleanup may dereference an `ERR_PTR` worker after `kthread_run_worker()` fails during simulator creation, causing a local kernel crash without evidence of information disclosure, privilege escalation, or remote reachability.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: this is a constrained cleanup error with an invalid pointer dereference and DoS-only impact, with no real UAF, repeated refcount mutation, controlled reclaim, or security-boundary primitive.

7. Call-site confidence

Call-site confidence: high

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

Patch: vdpa_sim: fix cleanup after worker creation failure [ Upstream
Commit: feafa109f031ed111f7f968e447c13985db498e0
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=feafa109f031ed111f7f968e447c13985db498e0

Changed files:
  drivers/vdpa/vdpa_sim/vdpa_sim.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=feafa109f031ed111f7f968e447c13985db498e0

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

The original Linux kernel CVE announcement for CVE-2026-90130 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90130

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:H
  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: 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).