CVE-2026-89814

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

drm/amdgpu: clamp the isolation index for rings outside a partition

adev->isolation[] has one slot per partition, but a ring that is not
assigned to one keeps AMDGPU_XCP_NO_PARTITION, which is ~0, so indexing
the array with it is out of bounds. SDMA submissions hit this on both
the isolation enforcement and the VM flush path and trip UBSAN.

Fall back to the first slot the way the cleaner shader path already
does, and stop taking the address before the ring type check that makes
it relevant.