CVE-2026-23129: dpll: Prevent duplicate registrations
In the Linux kernel, the following vulnerability has been resolved:
dpll: Prevent duplicate registrations
Modify the internal registration helpers dpllxaref{dpll,pin}add() to reject duplicate registration attempts.
Previously, if a caller attempted to register the same pin multiple times (with the same ops, priv, and cookie) on the same device, the core silently increments the reference count and return success. This behavior is incorrect because if the caller makes these duplicate registrations then for the first one dpllpinregistration is allocated and for others the associated dpllpinref.refcount is incremented. During the first unregistration the associated dpllpinregistration is freed and for others WARN is fired.
Fix this by updating the logic to return -EEXIST if a matching registration is found to enforce a strict "register once" policy.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
Modify the internal registration helpers dpll_xa_ref_{dpll,pin}_add() to detect matching duplicate registrations and return -EEXIST instead of incrementing the associated dpll_pin_ref.refcount and returning success.