CVE-2025-38217

Published Jul 4, 2025

Last updated a year ago

CVSS medium 4.7

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: hwmon: (ftsteutates) Fix TOCTOU race in fts_read() In the fts_read() function, when handling hwmon_pwm_auto_channels_temp, the code accesses the shared variable data->fan_source[channel] twice without holding any locks. It is first checked against FTS_FAN_SOURCE_INVALID, and if the check passes, it is read again when used as an argument to the BIT() macro. This creates a Time-of-Check to Time-of-Use (TOCTOU) race condition. Another thread executing fts_update_device() can modify the value of data->fan_source[channel] between the check and its use. If the value is changed to FTS_FAN_SOURCE_INVALID (0xff) during this window, the BIT() macro will be called with a large shift value (BIT(255)). A bit shift by a value greater than or equal to the type width is undefined behavior and can lead to a crash or incorrect values being returned to userspace. Fix this by reading data->fan_source[channel] into a local variable once, eliminating the race condition. Additionally, add a bounds check to ensure the value is less than BITS_PER_LONG before passing it to the BIT() macro, making the code more robust against undefined behavior. This possible bug was found by an experimental static analysis tool developed by our team.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Primary
Base score
4.7
Impact score
3.6
Exploitability score
1
Vector string
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
CWE-367

Social media

Hype score
Not currently trending

  1. CVE-2025-38217 Linux Kernel TOCTOU Race Condition in hwmon fts_read() Function https://t.co/P0aH2wTSSx Vulnerability Alert Subscriptions: https://t.co/hrQhy5uz4x

    @VulmonFeeds

    5 Jul 2025

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  2. CVE-2025-38217 In the Linux kernel, the following vulnerability has been resolved: hwmon: (ftsteutates) Fix TOCTOU race in fts_read() In the fts_read() function, when handling hwm… https://t.co/zxzz28Zkob

    @CVEnew

    4 Jul 2025

    198 Impressions

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Configurations

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References

Sources include official advisories and independent security research.