---
id: CVE-2025-71111
title: 'hwmon: (w83791d) Convert macros to functions to avoid TOCTOU'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  hwmon: (w83791d) Convert macros to functions to avoid TOCTOU

  The macro FAN_FROM_REG evaluates its arguments multiple times. When used
  in lockless contexts involving sh…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 <
    3dceb68f6ad33156032ef4da21a93d84059cca6d
  - >-
    Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 <
    bf5b03227f2e6d4360004886d268f9df8993ef8f
  - >-
    Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 <
    f2b579a0c37c0df19603d719894a942a295f634a
  - >-
    Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 <
    f94800fbc26ccf7c81eb791707b038a57aa39a18
  - >-
    Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 <
    a9fb6e8835a22f5796c1182ed612daed3fd273af
  - >-
    Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 <
    c8cf0c2bdcccc6634b6915ff793b844e12436680
  - >-
    Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 <
    670d7ef945d3a84683594429aea6ab2cdfa5ceb4
  - Linux 2.6.18
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-10T20:42:13.069072Z'
published: '2026-01-14'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T18:15:13.644Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-71111'
references:
  - url: 'https://git.kernel.org/stable/c/3dceb68f6ad33156032ef4da21a93d84059cca6d'
  - url: 'https://git.kernel.org/stable/c/bf5b03227f2e6d4360004886d268f9df8993ef8f'
  - url: 'https://git.kernel.org/stable/c/f2b579a0c37c0df19603d719894a942a295f634a'
  - url: 'https://git.kernel.org/stable/c/f94800fbc26ccf7c81eb791707b038a57aa39a18'
  - url: 'https://git.kernel.org/stable/c/a9fb6e8835a22f5796c1182ed612daed3fd273af'
  - url: 'https://git.kernel.org/stable/c/c8cf0c2bdcccc6634b6915ff793b844e12436680'
  - url: 'https://git.kernel.org/stable/c/670d7ef945d3a84683594429aea6ab2cdfa5ceb4'
tags:
  - cve.org
epss: 0.00105
epssPercentile: 0.01001
ingestedAt: '2026-10-19T18:35:50.134Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

hwmon: (w83791d) Convert macros to functions to avoid TOCTOU

The macro FAN_FROM_REG evaluates its arguments multiple times. When used
in lockless contexts involving shared driver data, this leads to
Time-of-Check to Time-of-Use (TOCTOU) race conditions, potentially
causing divide-by-zero errors.

Convert the macro to a static function. This guarantees that arguments
are evaluated only once (pass-by-value), preventing the race
conditions.

Additionally, in store_fan_div, move the calculation of the minimum
limit inside the update lock. This ensures that the read-modify-write
sequence operates on consistent data.

Adhere to the principle of minimal changes by only converting macros
that evaluate arguments multiple times and are used in lockless
contexts.

## Affected

- `Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 < 3dceb68f6ad33156032ef4da21a93d84059cca6d`
- `Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 < bf5b03227f2e6d4360004886d268f9df8993ef8f`
- `Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 < f2b579a0c37c0df19603d719894a942a295f634a`
- `Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 < f94800fbc26ccf7c81eb791707b038a57aa39a18`
- `Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 < a9fb6e8835a22f5796c1182ed612daed3fd273af`
- `Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 < c8cf0c2bdcccc6634b6915ff793b844e12436680`
- `Linux >= 9873964d6eb24bd0205394f9b791de9eddbcb855 < 670d7ef945d3a84683594429aea6ab2cdfa5ceb4`
- `Linux 2.6.18`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.