Cloudanix VulnDB

CVE-2025-39771

None

CVSS

—

EPSS

0.1%

Published

Sep 11, 2025

CISA due date

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Cloudanix analysis

Schedule a fix SSVC: Track

A bug in how the Linux kernel manages a power control chip on some devices can produce warning messages at startup until the system software is updated.

Exploitation
Other
Attacker needs
Local User
Complexity
Theoretical
Impact
Other
Component
OS kernel
Class
Other
Remediation
Patch
Effort
Medium
Patch risk
Low

What it actually does

Duplicate registration of a restart notifier handler during pca9450 I2C probe due to missing managed resource cleanup, resulting in kernel warnings from notifier_chain_register.

Why it matters to the business

Kernel warnings and potential boot-time instability on embedded systems using the pca9450 regulator; low security risk but requires kernel updates to restore clean operation.

How an attack unfolds

An attacker with local access could repeatedly load or probe the pca9450 driver module to trigger the already-registered notifier warning, but the issue does not enable code execution or privilege escalation.

How to fix it

Upgrade the Linux kernel to version 6.16.4 or apply commit 7a8c8aa0b0b2c62a0232bf868def85f3069ba7a7 that replaces register_restart_handler with devm_register_sys_off_handler in the pca9450 driver.

How to confirm the fix worked

Confirm kernel version is 6.16.4 or newer and inspect pca9450 driver source to verify use of devm_register_sys_off_handler instead of manual register_restart_handler.

Typical attack path

  1. Identify systems with pca9450 regulator hardware
  2. Trigger repeated driver probe or module reload
  3. Observe kernel warning in logs from notifier_chain_register

How to detect it

Search kernel logs for the strings 'pca9450_i2c_restart_handler already registered' and warnings originating from notifier_chain_register during i2c_device_probe or pca9450_i2c_probe.

  • notifier callback pca9450_i2c_restart_handler already registered
  • WARNING: kernel/notifier.c:23 at notifier_chain_register
  • pca9450_i2c_probe

What your security team should do

  • Apply kernel update to 6.16.4 or patched equivalent on affected hardware within standard maintenance windows
  • Review boot logs for notifier registration warnings on pca9450-based devices

The record

In the Linux kernel, the following vulnerability has been resolved: regulator: pca9450: Use devm_register_sys_off_handler With module test, there is error dump: ------------[ cut here ]------------ notifier callback pca9450_i2c_restart_handler already registered WARNING: kernel/notifier.c:23 at notifier_chain_register+0x5c/0x88, CPU#0: kworker/u16:3/50 Call trace: notifier_chain_register+0x5c/0x88 (P) atomic_notifier_chain_register+0x30/0x58 register_restart_handler+0x1c/0x28 pca9450_i2c_probe+0x418/0x538 i2c_device_probe+0x220/0x3d0 really_probe+0x114/0x410 __driver_probe_device+0xa0/0x150 driver_probe_device+0x40/0x114 __device_attach_driver+0xd4/0x12c So use devm_register_sys_off_handler to let kernel handle the resource free to avoid kernel dump.

Affected packages

Ecosystem Package Introduced Fixed
Debian:14 linux 0 No fix
Linux Kernel 6.16.0 6.16.4

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