Executive brief
The Linux kernel's thermal subsystem had a resource cleanup issue where removing a thermal zone could leave orphaned hardware monitoring (hwmon) sysfs attributes, preventing proper device removal. This was a code defect in the thermal zone management logic that could cause system stability issues when thermal zones are dynamically removed or drivers are unbound.
Technical details
A race condition existed in the thermal hwmon sysfs interface removal logic. When multiple thermal zones shared the same hwmon class device (based on zone type), and one thermal zone holding the hwmon device was removed, the removal function would skip cleanup if any sysfs attribute belonging to a different thermal zone remained. The fix moves the entire add/remove hwmon sysfs operation under a lock (thermal_hwmon_list_lock) and ensures the hwmon class device is fully removed when its parent thermal zone is deleted. The vulnerability is in the thermal/hwmon.c subsystem and affects the kernel's ability to cleanly unload thermal drivers.
Affected products
- Linux Linux kernel affected versions prior to the fix
Timeline
- 2026-09-17: disclosed
- 2026-09-17: patched