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Message-ID: <20231018013817.2391509-4-kuba@kernel.org>
Date: Tue, 17 Oct 2023 18:38:15 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
edumazet@...gle.com,
pabeni@...hat.com,
jiri@...nulli.us,
przemyslaw.kitszel@...el.com,
daniel@...earbox.net,
Jakub Kicinski <kuba@...nel.org>,
Jiri Pirko <jiri@...dia.com>
Subject: [PATCH net v2 3/5] 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 <jiri@...dia.com>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
v2: update the commit msg a bit
---
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 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);
--
2.41.0
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