[S390] cio: Use strict_strtoul() for attributes.

Make parsing of attribute writes handle incorrect input better.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/cio/ccwgroup.c b/drivers/s390/cio/ccwgroup.c
index fe1ad17..85b2e51 100644
--- a/drivers/s390/cio/ccwgroup.c
+++ b/drivers/s390/cio/ccwgroup.c
@@ -318,7 +318,7 @@
 {
 	struct ccwgroup_device *gdev;
 	struct ccwgroup_driver *gdrv;
-	unsigned int value;
+	unsigned long value;
 	int ret;
 
 	gdev = to_ccwgroupdev(dev);
@@ -329,7 +329,9 @@
 	if (!try_module_get(gdrv->owner))
 		return -EINVAL;
 
-	value = simple_strtoul(buf, NULL, 0);
+	ret = strict_strtoul(buf, 0, &value);
+	if (ret)
+		goto out;
 	ret = count;
 	if (value == 1)
 		ccwgroup_set_online(gdev);
@@ -337,6 +339,7 @@
 		ccwgroup_set_offline(gdev);
 	else
 		ret = -EINVAL;
+out:
 	module_put(gdrv->owner);
 	return ret;
 }