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

drm/amdgpu/userq: only accept doorbell BOs as queue doorbell

amdgpu_userq_get_doorbell_index() pins any BO passed as doorbell_handle
into the doorbell domain. For a regular BO, TTM moves it with
ttm_bo_move_null() and its contents are lost. Since an importer on the
same device gets the exporter's GEM object, a client can do this to a
buffer another client shared with it.

Reject BOs that were not created in the doorbell domain.

v2: drop the error message, use a local abo variable (Christian)

(cherry picked from commit f7497bbc19db4821c62b9d97b31c9086feb2d917)