CVE-2026-31486

About vulnerability

In the Linux kernel, the following vulnerability has been resolved: hwmon: (pmbus/core) Protect regulator operations with mutex The regulator operations pmbus_regulator_get_voltage(), pmbus_regulator_set_voltage(), and pmbus_regulator_list_voltage() access PMBus registers and shared data but were not protected by the update_lock mutex. This could lead to race conditions. However, adding mutex protection directly to these functions causes a deadlock because pmbus_regulator_notify() (which calls regulator_notifier_call_chain()) is often called with the mutex already held (e.g., from pmbus_fault_handler()). If a regulator callback then calls one of the now-protected voltage functions, it will attempt to acquire the same mutex. Rework pmbus_regulator_notify() to utilize a worker function to send notifications outside of the mutex protection. Events are stored as atomics in a per-page bitmask and processed by the worker. Initialize the worker and its associated data during regulator registration, and ensure it is cancelled on device removal using devm_add_action_or_reset(). While at it, remove the unnecessary include of linux/of.h. A flaw was found in the Linux kernel’s hwmon subsystem, specifically within the pmbus/core module. The regulator operations, which manage power management bus (PMBus) registers and shared data, were not adequately protected by a mutex (a mechanism to prevent simultaneous access to shared resources). This oversight could allow for race conditions, where multiple operations attempt to access or modify the same data concurrently, potentially leading to unpredictable system behavior or instability.

Live-patch status from KernelCare for each operating system.