[S390] uaccess error handling.

Consider return values for all user space access function and
return -EFAULT on error.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c
index 2001767..5b33f82 100644
--- a/arch/s390/kernel/compat_linux.c
+++ b/arch/s390/kernel/compat_linux.c
@@ -757,7 +757,9 @@
 			    put_user(oldlen, (u32 __user *)compat_ptr(tmp.oldlenp)))
 				error = -EFAULT;
 		}
-		copy_to_user(args->__unused, tmp.__unused, sizeof(tmp.__unused));
+		if (copy_to_user(args->__unused, tmp.__unused,
+				 sizeof(tmp.__unused)))
+			error = -EFAULT;
 	}
 	return error;
 }