[CVE-2026-68403][LOW] wifi: brcmfmac: initialize SDIO data work before cleanup [ Upstream

[CVE-2026-68403][LOW] wifi: brcmfmac: initialize SDIO data work before cleanup [ Upstream

[AL-KERNEL]

CVE: CVE-2026-68403
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: wifi: brcmfmac: initialize SDIO data work before cleanup [ Upstream
Commit: f50a2b9e57a751e70ae9a272875d80d39eaccd6a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f50a2b9e57a751e70ae9a272875d80d39eaccd6a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68403
Analysis date: Mon, 10 Aug 2026 18:08:29 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
An early brcmfmac SDIO probe failure can call cleanup before bus datawork is initialized, causing an invalid work drain and possible local DoS only in constrained debug or panic_on_warn style conditions.

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

The original Linux kernel CVE announcement for CVE-2026-68403 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68403

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-2026-68403	LOW	CHECK WITH IMPACT FROM ORIG NN IMPORTANT	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-665;CWE-703;CWE-754;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'An SDIO brcmfmac probe error path can reach brcmf_sdio_remove after alloc_ordered_workqueue fails while bus datawork has not yet been initialized with INIT_WORK. The cleanup path then drains or cancels an embedded work item that is not a valid work object, which is reported by DEBUG_OBJECTS as an invalid work drain. For the CVSS the PR:L is used only for the paranoid interpretation where a local user can influence memory pressure and a driver probe or recovery path, while the more typical case requires administrative or device management control. The issue is not network reachable and requires a local driver initialization failure path. Impact is denial of service at most, mainly warning or crash in debug or panic_on_warn style configurations, with no supported confidentiality or integrity impact.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)	YES	REMOTE INIT SIMPLEFIX ERRORPATH NETWORK  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	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

* Requires admin/root/device-management path in typical deployments: -2. Triggering probe/remove or driver rebind normally requires administrative control or device-management privileges.
* Hard or unreliable condition: -1. The failing path requires alloc_ordered_workqueue() to fail at a narrow point during SDIO probe.
* Rare or configuration-dependent exposure: -1. This is specific to brcmfmac SDIO device initialization and an early allocation failure path.
* Availability concern: +1 paranoid only. DEBUG_OBJECTS reports invalid work drain, and in debug or panic_on_warn configurations this may become a crash.
* No remote/network trigger: +0. This is not triggered by WiFi traffic.
* No demonstrated memory corruption primitive: +0. The patch shows uninitialized work_struct cancellation, not UAF reclaim, OOB write, double free, callback control, or arbitrary write.
* No LPE signal: +0. There is no supported path to privilege escalation.

## 3. Reachability analysis

The realistic trigger is local and tied to SDIO driver initialization failure. A normal unprivileged user generally cannot directly force this path, though a paranoid interpretation may consider local memory pressure combined with device reprobe or recovery. Namespaces do not materially lower the requirement unless a container is unusually delegated device or module management. The path is not remotely reachable through network packets and is not a common default server exposure.

Call-site confidence: high, because the patch and commit describe the exact probe failure path and cleanup call behavior.

## 4. Severity interpretation

This behaves like a Low-like or ordinary Moderate robustness issue, not an Important-class vulnerability. The theoretical failure is an invalid work drain during cleanup of a partially initialized object. Realistic impact is warning or DoS in debug or panic_on_warn configurations. There is no evidence of attacker-controlled reclaim, stale callback execution, writable UAF, object replacement, confidentiality impact, or integrity impact.

## 5. One-sentence report phrase

An early brcmfmac SDIO probe failure can call cleanup before bus datawork is initialized, causing an invalid work drain and possible local DoS only in constrained debug or panic_on_warn style conditions.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

The issue is a constrained cleanup-ordering bug with no network reachability, no practical unprivileged trigger, and no demonstrated memory corruption or privilege-escalation primitive.

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

Patch: wifi: brcmfmac: initialize SDIO data work before cleanup [ Upstream
Commit: f50a2b9e57a751e70ae9a272875d80d39eaccd6a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f50a2b9e57a751e70ae9a272875d80d39eaccd6a

Changed files:
  drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.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=f50a2b9e57a751e70ae9a272875d80d39eaccd6a

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

The original Linux kernel CVE announcement for CVE-2026-68403 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68403

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).