[PATCH] copy_namespace ENOMEM fix

From: Marcus Alanen <maalanen@ra.abo.fi>

The copy_tree() function can return NULL, so this checks for it.

fs/namespace.c

@@ -817,12 +817,16 @@ int copy_namespace(int flags, struct task_struct *tsk)
 
 	atomic_set(&new_ns->count, 1);
 	init_rwsem(&new_ns->sem);
-	new_ns->root = NULL;
 	INIT_LIST_HEAD(&new_ns->list);
 
 	down_write(&tsk->namespace->sem);
 	/* First pass: copy the tree topology */
 	new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root);
+	if (!new_ns->root) {
+		up_write(&tsk->namespace->sem);
+		kfree(new_ns);
+		goto out;
+	}
 	spin_lock(&vfsmount_lock);
 	list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
 	spin_unlock(&vfsmount_lock);