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Message-ID: <20231016201657.1754763-4-kuba@kernel.org>
Date: Mon, 16 Oct 2023 13:16:55 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
edumazet@...gle.com,
pabeni@...hat.com,
Jakub Kicinski <kuba@...nel.org>,
jiri@...nulli.us
Subject: [PATCH net 3/5] net: avoid UAF on deleted altname
Altnames are accessed under RCU (__dev_get_by_name())
but freed by kfree() with no synchronization point.
Because the name nodes don't hold a reference on the netdevice
either, take the heavier approach of inserting synchronization
points. Subsequent patch will remove the one added on device
deletion path.
Fixes: ff92741270bf ("net: introduce name_node struct to be used in hashlist")
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
CC: jiri@...nulli.us
---
net/core/dev.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index f4fa2692cf6d..7d5107cd5792 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;
@@ -10937,6 +10938,7 @@ 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. */
@@ -10964,6 +10966,9 @@ 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);
--
2.41.0
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