Return EINVAL from write if the size is larger than
allowed.  Do this before allocating kernel memory for
the bogus size, which could lead to OOM.
Reported-by: NSasha Levin <levinsasha928@gmail.com>
Tested-by: NJana Saout <jana@saout.de>
Signed-off-by: NDavid Teigland <teigland@redhat.com>