CVE-2024-27027: dpll: fix dpll_xa_ref_*_del() for multiple registrations

Description

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.

Classification

CVE ID: CVE-2024-27027

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.05% (probability of being exploited)

EPSS Percentile: 17.83% (scored less or equal to compared to others)

EPSS Date: 2025-02-04 (when was this score calculated)

References

https://git.kernel.org/stable/c/769324eb35143462542cdb15483cdaf4877bf661
https://git.kernel.org/stable/c/b27e32e9367dac024cd6f61f22655714f483fd67
https://git.kernel.org/stable/c/b446631f355ece73b13c311dd712c47381a23172

Timeline