CVE-2026-68103

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

drm/amdgpu: reject mapping a reserved doorbell to a new queue

When creating an user-queue, the user space provides a doorbell BO handle and an offset within the bo to obtain a doorbell.

However current implementation using xa_store_irq() to store a doorbell, which allows a later queue created with the same BO and offset parameters to overwrite an existing queue and doorbell mapping.

This can cause problems like misrouting fence IRQ processing to a wrong queue, and mislead the cleanup process of one queue erasing the mapping of another queue.

This commit fixes this issue by replacing xa_store_irq with xa_insert_irq, which rejects mapping a reserved doorbell to a newly created queue

(cherry picked from commit 6244eae22966350db52faf9c1369d3b2ffc5de4e)