security/selinux/ss: Use kstrdup

Use kstrdup when the goal of an allocation is copy a string into the
allocated region.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression from,to;
expression flag,E1,E2;
statement S;
@@

-  to = kmalloc(strlen(from) + 1,flag);
+  to = kstrdup(from, flag);
   ... when != \(from = E1 \| to = E1 \)
   if (to==NULL || ...) S
   ... when != \(from = E2 \| to = E2 \)
-  strcpy(to, from);
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

security/selinux/ss/policydb.c

@@ -156,12 +156,11 @@ static int roles_init(struct policydb *p)
 		rc = -EINVAL;
 		goto out_free_role;
 	}
-	key = kmalloc(strlen(OBJECT_R) + 1, GFP_KERNEL);
+	key = kstrdup(OBJECT_R, GFP_KERNEL);
 	if (!key) {
 		rc = -ENOMEM;
 		goto out_free_role;
 	}
-	strcpy(key, OBJECT_R);
 	rc = hashtab_insert(p->p_roles.table, key, role);
 	if (rc)
 		goto out_free_key;