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net: add rcu safety to rtnl_prop_list_size()

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rtnl_prop_list_size() can be called while alternative names
are added or removed concurrently.

if_nlmsg_size() / rtnl_calcit() can indeed be called
without RTNL held.

Use explicit RCU protection to avoid UAF.

Fixes: 88f4fb0c74 ("net: rtnetlink: put alternative names to getlink message")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20240209181248.96637-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-02-09 18:12:48 +00:00 committed by Jakub Kicinski
parent 3e36031cc0
commit 9f30831390
2 changed files with 10 additions and 7 deletions
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2
net/core/dev.c
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@ -336,7 +336,7 @@ int netdev_name_node_alt_create(struct net_device *dev, const char *name)
return -ENOMEM;
netdev_name_node_add(net, name_node);
/* The node that holds dev->name acts as a head of per-device list. */
list_add_tail(&name_node->list, &dev->name_node->list);
list_add_tail_rcu(&name_node->list, &dev->name_node->list);
return 0;
}

15
net/core/rtnetlink.c
View File

@ -1020,14 +1020,17 @@ static size_t rtnl_xdp_size(void)
static size_t rtnl_prop_list_size(const struct net_device *dev)
{
struct netdev_name_node *name_node;
size_t size;
unsigned int cnt = 0;
if (list_empty(&dev->name_node->list))
rcu_read_lock();
list_for_each_entry_rcu(name_node, &dev->name_node->list, list)
cnt++;
rcu_read_unlock();
if (!cnt)
return 0;
size = nla_total_size(0);
list_for_each_entry(name_node, &dev->name_node->list, list)
size += nla_total_size(ALTIFNAMSIZ);
return size;
return nla_total_size(0) + cnt * nla_total_size(ALTIFNAMSIZ);
}
static size_t rtnl_proto_down_size(const struct net_device *dev)