Commit 1a83f4a7 authored by Jakub Kicinski's avatar Jakub Kicinski Committed by Paolo Abeni
Browse files

net: avoid UAF on deleted altname 



Altnames are accessed under RCU (dev_get_by_name_rcu())
but freed by kfree() with no synchronization point.

Each node has one or two allocations (node and a variable-size
name, sometimes the name is netdev->name). Adding rcu_heads
here is a bit tedious. Besides most code which unlists the names
already has rcu barriers - so take the simpler approach of adding
synchronize_rcu(). Note that the one on the unregistration path
(which matters more) is removed by the next fix.

Fixes: ff927412 ("net: introduce name_node struct to be used in hashlist")
Reviewed-by: default avatarJiri Pirko <jiri@nvidia.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 7663d522

net/core/dev.c

+6 −1
Original line number Diff line number Diff line
@@ -345,7 +345,6 @@ int netdev_name_node_alt_create(struct net_device *dev, const char *name) 
static void __netdev_name_node_alt_destroy(struct netdev_name_node *name_node)

{

	list_del(&name_node->list);

	netdev_name_node_del(name_node);

	kfree(name_node->name);

	netdev_name_node_free(name_node);

}
@@ -364,6 +363,8 @@ int netdev_name_node_alt_destroy(struct net_device *dev, const char *name) 
	if (name_node == dev->name_node || name_node->dev != dev)

		return -EINVAL;



	netdev_name_node_del(name_node);

	synchronize_rcu();

	__netdev_name_node_alt_destroy(name_node);



	return 0;
@@ -10941,6 +10942,7 @@ void unregister_netdevice_many_notify(struct list_head *head, 
	synchronize_net();



	list_for_each_entry(dev, head, unreg_list) {

		struct netdev_name_node *name_node;

		struct sk_buff *skb = NULL;



		/* Shutdown queueing discipline. */
@@ -10968,6 +10970,9 @@ void unregister_netdevice_many_notify(struct list_head *head, 
		dev_uc_flush(dev);

		dev_mc_flush(dev);



		netdev_for_each_altname(dev, name_node)

			netdev_name_node_del(name_node);

		synchronize_rcu();

		netdev_name_node_alt_flush(dev);

		netdev_name_node_free(dev->name_node);