A lock ordering bug in the Linux kernel’s hardware monitoring (hwmon) subsystem allows a deadlock to occur when sysfs devices are unregistered while the OCC (On‑Chip Controller) lock is held. The flaw arises because the unregister path holds the OCC mutex and then waits for active sysfs callbacks to drain, which in turn may request the OCC lock again, creating a circular dependency. This deadlock can halt kernel operations involving hwmon, potentially freezing the system or causing instability, and thereby constitutes a denial‑of‑service condition. The bug was identified through static analysis and validated with a reproducible test harness that demonstrates the lock dependency. The vulnerability is related to improper synchronization and deadlock conditions caused by inconsistent lock ordering within the kernel. It specifically targets the coordination between the OCC lock and the sysfs callback drain mechanism.

This vulnerability affects the Linux kernel, all versions maintained by the Linux kernel developers that implement the hwmon subsystem prior to the patch commit. The CVE data does not specify exact affected releases, but the fix was applied in the mainline kernel, implying all previous kernel versions are potentially vulnerable.

The risk of exploitation is not quantified with a CVSS score because no official score is published, and the EPSS score is unavailable. The issue is not listed in CISA’s KEV catalog, and no public exploit has been reported. However, the bug can be triggered by operations that invoke occ_shutdown or hwmon device removal, which may be possible only by processes with elevated privileges. Therefore, the window for malicious exploitation is limited to privileged contexts, but an attacker with such access could induce a deadlock and disrupt service.