virtio-net: Add validation for used length

commit ad993a95c508417acdeb15244109e009e50d8758 upstream.

This adds validation for used length (might come
from an untrusted device) to avoid data corruption
or loss.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210531135852.113-1-xieyongji@bytedance.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Larry: backport to 5.4.y. Minor conflict resolved due to missing commit 9ce6146ec7b50
  virtio_net: Add XDP frame size in two code paths ]
Signed-off-by: Larry Bassel <larry.bassel@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>