Make sure that even in error situations we do not use copy_to_user
on uninitialized kernel memory.

Cc: stable@vger.kernel.org # 3.19+
Signed-off-by: NSebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>