// For flags

CVE-2025-38217

hwmon: (ftsteutates) Fix TOCTOU race in fts_read()

Severity Score

7.1
*CVSS v3

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

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.

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.

The SUSE Linux Enterprise 15 SP6 Azure kernel was updated to receive various security bug fixes.

*Credits: N/A
CVSS Scores
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High
Attack Vector
Local
Attack Complexity
Medium
Authentication
None
Confidentiality
Partial
Integrity
None
Availability
Complete
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2025-04-16 CVE Reserved
  • 2025-07-04 CVE Published
  • 2025-07-28 CVE Updated
  • 2025-08-05 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 6.3 < 6.6.95
Search vendor "Linux" for product "Linux Kernel" and version " >= 6.3 < 6.6.95"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 6.3 < 6.12.35
Search vendor "Linux" for product "Linux Kernel" and version " >= 6.3 < 6.12.35"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 6.3 < 6.15.4
Search vendor "Linux" for product "Linux Kernel" and version " >= 6.3 < 6.15.4"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 6.3 < 6.16
Search vendor "Linux" for product "Linux Kernel" and version " >= 6.3 < 6.16"
en
Affected