CVE-2024-27027: Undefined Security Weakness

In the Linux kernel, the following vulnerability has been resolved:

dpll: fix dpll_xa_ref_*_del() for multiple registrations

Currently, if there are multiple registrations of the same pin on the same dpll device, following warnings are observed: WARNING: CPU: 5 PID: 2212 at drivers/dpll/dpll_core.c:143 dpll_xa_ref_pin_del.isra.0+0x21e/0x230 WARNING: CPU: 5 PID: 2212 at drivers/dpll/dpll_core.c:223 __dpll_pin_unregister+0x2b3/0x2c0

The problem is, that in both dpll_xa_ref_dpll_del() and dpll_xa_ref_pin_del() registration is only removed from list in case the reference count drops to zero. That is wrong, the registration has to be removed always.

To fix this, remove the registration from the list and free it unconditionally, instead of doing it only when the ref reference counter reaches zero.