selinux: fix bad cleanup on error in hashtab_duplicate()

The code attempts to free the 'new' pointer using kmem_cache_free(),
which is wrong because this function isn't responsible of freeing it.
Instead, the function should free new->htable and clear the contents of
*new (to prevent double-free).

Cc: stable@vger.kernel.org
Fixes: c7c556f1e8 ("selinux: refactor changing booleans")
Reported-by: Wander Lairson Costa <wander@redhat.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/ss/hashtab.c

@@ -179,7 +179,8 @@ int hashtab_duplicate(struct hashtab *new, struct hashtab *orig,
 			kmem_cache_free(hashtab_node_cachep, cur);
 		}
 	}
-	kmem_cache_free(hashtab_node_cachep, new);
+	kfree(new->htable);
+	memset(new, 0, sizeof(*new));
 	return -ENOMEM;
 }