[CVE-2026-64454][LOW] usb: dwc3: run gadget disconnect from sleepable suspend context

[CVE-2026-64454][LOW] usb: dwc3: run gadget disconnect from sleepable suspend context

[AL-KERNEL]

CVE: CVE-2026-64454
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: usb: dwc3: run gadget disconnect from sleepable suspend context
Commit: b399be2958456efe1b64b19c55a54a24e9035769
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b399be2958456efe1b64b19c55a54a24e9035769
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64454
Analysis date: Sat, 25 Jul 2026 07:59:58 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
The DWC3 gadget suspend path could invoke a gadget disconnect callback with IRQs disabled, allowing a local privileged or delegated device-management context to trigger a sleep-in-atomic warning or suspend-path DoS, but no memory corruption or privilege escalation primitive is evident.

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

The original Linux kernel CVE announcement for CVE-2026-64454 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64454

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
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CVE-2026-64454	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-667;CWE-703;CWE-755;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'The DWC3 gadget suspend path can invoke the gadget driver disconnect callback while IRQs are still disabled. If that disconnect callback calls a sleepable function, the kernel may report sleeping function called from invalid context and the suspend or disconnect path can fail or hang. For the CVSS the PR:L is used in the paranoid score because some embedded or containerized deployments may delegate USB gadget or power management control to a reduced privilege service account rather than full host root. The issue is not network reachable and is triggered through local USB gadget or suspend control paths. Impact is primarily denial of service or reliability degradation, with no supported evidence of memory corruption or privilege escalation from the shown code path.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)	YES	LOCK DANGER USB INIT LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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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/CAP_* in typical deployments: -2. Triggering this path normally requires control over USB gadget configuration, gadget driver binding, or system suspend paths.
* Rare or configuration-dependent subsystem: -1. DWC3 gadget mode is common in embedded systems but not a broad default server or desktop exposure.
* Availability impact realistic: +1. The observed effect is Lockdep reporting sleeping function called from invalid context, with possible suspend or disconnect failure. Strong host-wide DoS is not demonstrated.

Conservative total is floored to 0.

Paranoid signals:

* Local reduced-privilege trigger: +1. Some embedded systems may delegate USB gadget or power-management operations to a service account, container root, or reduced-capability process.
* Availability impact realistic: +1. A sleepable disconnect callback executed with IRQs disabled can cause reliability failure, warning, hang, or panic only in stricter configurations such as panic_on_warn.
* Rare or configuration-dependent subsystem: -1. The issue depends on DWC3 gadget mode, async callbacks, suspend, and a disconnect callback that may sleep.

Paranoid total: 1.

No memory corruption, UAF, OOB write, object lifetime corruption, page-cache corruption, security-boundary bypass, or plausible LPE signal is supported by the patch.

## 3. Reachability analysis

The bug is local and not network reachable. It is triggered through the USB DWC3 gadget suspend path, specifically when `dwc3_gadget_suspend()` calls the gadget disconnect callback while IRQs remain disabled.

In typical deployments, triggering requires administrative or device-management privileges. Namespace or container delegation could lower the practical privilege requirement only on specialized embedded products where USB gadget or suspend control is exposed to less privileged services.

The path is not broadly default-enabled on general-purpose systems. Realistic exploitation conditions require DWC3 gadget mode, async callbacks, suspend activity, and a disconnect callback that performs sleepable operations.

Call-site confidence: high, because the provided patch includes the affected caller and the fixed helper path.

## 4. Severity interpretation

This behaves like a low-end ordinary Moderate or Low-like reliability issue, not an Important-class kernel vulnerability.

Theoretical impact is local DoS or suspend-path instability. Realistic evidence shows a Lockdep sleeping-in-invalid-context warning. The patch does not show a memory corruption primitive, stale object reuse, attacker-controlled reclaim, callback pointer corruption, privilege escalation path, information disclosure, or integrity impact.

## 5. One-sentence report phrase

The DWC3 gadget suspend path could invoke a gadget disconnect callback with IRQs disabled, allowing a local privileged or delegated device-management context to trigger a sleep-in-atomic warning or suspend-path DoS, but no memory corruption or privilege escalation primitive is evident.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed for urgent security triage because the issue is local, configuration-dependent, mainly reliability-oriented, and lacks evidence of memory corruption, privilege escalation, or a security-boundary bypass.

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

Patch: usb: dwc3: run gadget disconnect from sleepable suspend context
Commit: b399be2958456efe1b64b19c55a54a24e9035769
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b399be2958456efe1b64b19c55a54a24e9035769

Commit description:

dwc3_gadget_suspend() takes dwc->lock with IRQs disabled and then calls
dwc3_disconnect_gadget().  For async callbacks that helper only uses
plain spin_unlock()/spin_lock(), so the gadget ->disconnect() callback
still runs with IRQs disabled and any sleepable callback trips Lockdep.

This issue was found by our static analysis tool and then manually
reviewed against the current tree.

The grounded PoC kept the dwc3_gadget_suspend() ->
dwc3_disconnect_gadget() -> gadget_driver->disconnect() chain, and
Lockdep reported:

  BUG: sleeping function called from invalid context
  gadget_disconnect+0x21/0x39 [vuln_msv]
  dwc3_gadget_suspend.constprop.0+0x2b/0x42 [vuln_msv]

Keep the disconnect callback selection in one common helper, but add a
sleepable suspend-side wrapper which snapshots the callback under
dwc->lock and then runs it after spin_unlock_irqrestore().  The regular
event path still uses the existing spin_unlock()/spin_lock() window.

Fixes: c854087 ("usb: dwc3: gadget: Improve dwc3_gadget_suspend() and dwc3_gadget_resume()")
Cc: stable <stable@kernel.org>
Signed-off-by: Runyu Xiao <runyu.xiao@seu.edu.cn>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://patch.msgid.link/20260612052005.3849659-1-runyu.xiao@seu.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/usb/dwc3/gadget.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=b399be2958456efe1b64b19c55a54a24e9035769

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

The original Linux kernel CVE announcement for CVE-2026-64454 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64454

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: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: 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).