drm/v3d: Reject invalid indirect BO handle in indirect CSD setup

drm/v3d: Reject invalid indirect BO handle in indirect CSD setup

v3d_get_cpu_indirect_csd_params() looks up the indirect buffer object
from a userspace-supplied handle but never checks the result. A bogus
or stale handle makes drm_gem_object_lookup() return NULL, which is
then stored in info->indirect and only dereferenced later when the
indirect CSD job runs, turning a userspace mistake into a NULL pointer
dereference in the kernel.

Bail out with -ENOENT as soon as the lookup fails, so the bad handle is
rejected at submission time.

Fixes: 18b8413b25b7 ("drm/v3d: Create a CPU job extension for a indirect CSD job")
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Link: https://patch.msgid.link/20260703-v3d-cpu-job-fixes-v3-2-bc51b1f3eeb5@igalia.com