libceph: replace BUG_ON with bounds check for map->max_osd

libceph: replace BUG_ON with bounds check for map->max_osd

commit ec3797f043756a94ea2d0f106022e14ac4946c02 upstream.

OSD indexes come from untrusted network packets. Boundary checks are
added to validate these against map->max_osd.

[ idryomov: drop BUG_ON in ceph_get_primary_affinity(), minor cosmetic
  edits ]

Cc: stable@vger.kernel.org
Signed-off-by: ziming zhang <ezrakiez@gmail.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>