From 1a83f4a7c156fa6bbd6b530e89fa3270bf3d9d1b Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 17 Oct 2023 18:38:15 -0700 Subject: 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: ff92741270bf ("net: introduce name_node struct to be used in hashlist") Reviewed-by: Jiri Pirko Signed-off-by: Jakub Kicinski Signed-off-by: Paolo Abeni --- net/core/dev.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'net') diff --git a/net/core/dev.c b/net/core/dev.c index ae557193b77c..559705aeefe4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -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); -- cgit v1.2.3