If we do a zero size allocation then it will oops. Also we can't be
sure the user passes us a NUL terminated string so I've added a
terminator.
This code can only be triggered by root.
Reported-by: Nico Golde <nico@ngolde.de> Reported-by: Fabian Yamaguchi <fabs@goesec.de> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Dan Williams <dcbw@redhat.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>