Normally the range->len is set to default value (U64_MAX), but when it's
not default value, we should check if the range overflows.

And if it overflows, return -EINVAL before doing anything.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>