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net: avoid UAF on deleted altname

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commit 1a83f4a7c1 upstream.

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: ff92741270 ("net: introduce name_node struct to be used in hashlist")
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jakub Kicinski 2023-10-17 18:38:15 -07:00 committed by Greg Kroah-Hartman
parent 1cf912054a
commit b92433493b
1 changed files with 6 additions and 1 deletions
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7
net/core/dev.c
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@ -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;
@ -10835,6 +10836,7 @@ void unregister_netdevice_many(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. */
@ -10860,6 +10862,9 @@ void unregister_netdevice_many(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);