[CVE-2026-72240][LOW] mfd: sm501: Fix reference leak on failed device registration

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

CVE: CVE-2026-72240
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: mfd: sm501: Fix reference leak on failed device registration
Commit: bbb1ecaed4ed7680e63d3a0f143f03de32de5d6e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bbb1ecaed4ed7680e63d3a0f143f03de32de5d6e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72240
Analysis date: Sun, 16 Aug 2026 08:01:06 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A reference leak in the SM501 MFD driver failed registration path can leave initialized platform device references unreleased, but exploitation appears limited to privileged local device-management scenarios and resource exhaustion only.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-72240 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72240

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-2026-72240	LOW	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:H/UI:N/S:U/C:N/I:N/A:H';*CWE-772;*CWE-401;CWE-404;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.4';DESCR 'A reference leak in the SM501 MFD driver occurs when platform_device_register fails after the embedded device object has already been initialized. The error path returned without dropping the platform device reference, so repeated failed registration attempts could accumulate leaked references and consume kernel resources. For the CVSS the PR:H value is used because reliable triggering requires administrative control over driver probing or device registration paths. The issue is not network reachable and is not triggered by packet traffic or remote input. Impact is denial of service through resource leakage only, with no supported UAF, OOB access, information disclosure, or privilege escalation primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 0)	YES	INIT SIMPLEFIX LEAK HARDWARE LINUS 	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 0
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Triggered positive signals:

* Real lifetime or reference management issue: +1. The failed `platform_device_register()` path leaks a device reference because `device_initialize()` has already run and the error path did not call `platform_device_put()`.
* Availability impact realistic: +1 only in a sustained-abuse interpretation. Repeated failed registrations could accumulate leaked references and consume kernel resources.

Triggered negative signals:

* Requires admin/root/device-management control in typical deployments: -2. Reliable triggering requires control over driver probing, device registration, module or platform device setup, or fault conditions in a privileged driver path.
* Rare or hardware-specific subsystem: -1 can be considered, but the score is already floored at 0. SM501 is not a broad default kernel attack surface.

Not triggered:

* No remote or network reachability.
* No local unprivileged trigger shown.
* No UAF, double free, OOB access, arbitrary write, type confusion, callback corruption, or attacker-controlled reclaim.
* No plausible privilege escalation primitive.
* No confidentiality or integrity impact supported by the patch.

## 3. Reachability analysis

The bug is reachable through the SM501 MFD driver device registration error path. In normal deployments, an attacker would need administrative or equivalent device-management control to cause repeated probing or failed registration. Namespaces or containers do not materially reduce the privilege requirement unless the environment delegates real host device-management capabilities, which would already be highly privileged. The path is not network reachable and is not exposed through ordinary packet processing, syscalls, or unprivileged local APIs. Call-site confidence: high, because the relevant failure path and fix are directly shown in the patch.

## 4. Severity interpretation

This behaves like a Low-like or ordinary Moderate resource-management bug, not an actionable Moderate or Important kernel vulnerability. The realistic impact is a reference leak and possible resource exhaustion only under repeated privileged failure conditions. Theoretical impact does not extend to memory corruption or privilege escalation based on the supplied patch and normal kernel lifetime semantics.

## 5. One-sentence report phrase

A reference leak in the SM501 MFD driver failed registration path can leave initialized platform device references unreleased, but exploitation appears limited to privileged local device-management scenarios and resource exhaustion only.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed for practical triage because it is a privileged local reference leak with no supported memory corruption, security-boundary bypass, network exposure, or privilege escalation primitive.

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

Patch: mfd: sm501: Fix reference leak on failed device registration
Commit: bbb1ecaed4ed7680e63d3a0f143f03de32de5d6e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bbb1ecaed4ed7680e63d3a0f143f03de32de5d6e

Commit description:

When platform_device_register() fails in sm501_register_device(), the
embedded struct device in pdev has already been initialized by
device_initialize(), but the failure path only reports the error and
returns without dropping the device reference for the current platform
device:

  sm501_register_device()
    -> platform_device_register(pdev)
       -> device_initialize(&pdev->dev)
       -> setup_pdev_dma_masks(pdev)
       -> platform_device_add(pdev)

This leads to a reference leak when platform_device_register() fails.
Fix this by calling platform_device_put() before returning the error.

The issue was identified by a static analysis tool I developed and
confirmed by manual review.

Fixes: b6d6454 ("[PATCH] mfd: SM501 core driver")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
Link: https://patch.msgid.link/20260415162627.3558789-1-lgs201920130244@gmail.com
Signed-off-by: Lee Jones <lee@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/mfd/sm501.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=bbb1ecaed4ed7680e63d3a0f143f03de32de5d6e

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

The original Linux kernel CVE announcement for CVE-2026-72240 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72240

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:L/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.4

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: 0

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).