CVE-2026-98566: drm/imagination: clamp freelist reconstruction requests

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

drm/imagination: clamp freelist reconstruction requests

The firmware reconstruction count controls accesses to the request's fixed freelist ID array and the copy into the fixed response array. Neither access currently bounds the count to those protocol arrays.

Clamp the count to the request capacity, which is shared by the response layout, and use that count consistently for reconstruction and response publication. Keep the firmware recovery exchange instead of dropping an oversized request without a response, as discussed with the firmware maintainer.

The issue was found by our static-analysis tool.