strnlen_user is supposed to return then length count + 1 if no terminating \0
is found, and it should return 0 on exception.  Found by David Howells
<dhowells@redhat.com>.
Signed-off-by: NGerald Schaefer <geraldsc@de.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-By: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>