In the Linux kernel, the following vulnerability has been resolved:
hwmon: (pmbus) Fix passing events to regulator core
Sashiko reports:
Commit 754bd2b4a084 (“hwmon: (pmbus/core) Protect regulator operations with
mutex”) introduced a worker to batch regulator events over time using
atomic_or(). The delayed worker then passes the combined bitmask unmodified
to regulator_notifier_call_chain().
The core regulator subsystem’s regulator_handle_critical() function
evaluates the event parameter using a strict switch statement. If
multiple distinct faults occur before the worker runs (e.g.,
REGULATOR_EVENT_UNDER_VOLTAGE | REGULATOR_EVENT_OVER_CURRENT), the combined
bitmask fails to match any case. This leaves the reason as NULL and
completely bypasses the critical hw_protection_trigger().
Fix the problem by passing events bit by bit to the regulator event
handler.
