CVE-2025-71111: hwmon: (w83791d) Convert macros to functions to avoid TOCTOU

Severity: medium (CVSS 4.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-01-14 · updated 2026-10-19
Weakness: CWE-367

Description

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 products

Linux kernel: from 2.6.18.1 before 5.10.248; from 5.11 before 5.15.198; from 5.16 before 6.1.160; from 6.2 before 6.6.120; from 6.7 before 6.12.64; from 6.13 before 6.18.3 — fixed in 5.10.248, 5.15.198, 6.1.160, 6.12.64, 6.18.3, 6.6.120

How to fix

Upgrade to a fixed version: Linux kernel 5.10.248, 5.15.198, 6.1.160, 6.12.64. Check the vendor advisory for mitigations.

References

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