2022-09-15 01:22:00

by Ziyang Xuan (William)

Subject: [PATCH net-next] net/af_packet: registration process optimization in packet_init()

Now, register_pernet_subsys() and register_netdevice_notifier() are both
after sock_register(). It can create PF_PACKET socket and process socket
once sock_register() successfully. It is possible PF_PACKET socket is
creating but register_pernet_subsys() and register_netdevice_notifier()
are not registered yet. Thus net->packet.sklist_lock and net->packet.sklist
will be accessed without initialization that is done in packet_net_init().
Although this is a low probability scenario.

Move register_pernet_subsys() and register_netdevice_notifier() to the
front in packet_init(). Correspondingly, adjust the unregister process
in packet_exit().

Signed-off-by: Ziyang Xuan <[email protected]>
---
net/packet/af_packet.c | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 5cbe07116e04..52cc9931b367 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -4725,37 +4725,37 @@ static struct pernet_operations packet_net_ops = {

static void __exit packet_exit(void)
{
- unregister_netdevice_notifier(&packet_netdev_notifier);
- unregister_pernet_subsys(&packet_net_ops);
sock_unregister(PF_PACKET);
proto_unregister(&packet_proto);
+ unregister_netdevice_notifier(&packet_netdev_notifier);
+ unregister_pernet_subsys(&packet_net_ops);
}

static int __init packet_init(void)
{
int rc;

- rc = proto_register(&packet_proto, 0);
- if (rc)
- goto out;
- rc = sock_register(&packet_family_ops);
- if (rc)
- goto out_proto;
rc = register_pernet_subsys(&packet_net_ops);
if (rc)
- goto out_sock;
+ goto out;
rc = register_netdevice_notifier(&packet_netdev_notifier);
if (rc)
goto out_pernet;
+ rc = proto_register(&packet_proto, 0);
+ if (rc)
+ goto out_notifier;
+ rc = sock_register(&packet_family_ops);
+ if (rc)
+ goto out_proto;

return 0;

-out_pernet:
- unregister_pernet_subsys(&packet_net_ops);
-out_sock:
- sock_unregister(PF_PACKET);
out_proto:
proto_unregister(&packet_proto);
+out_notifier:
+ unregister_netdevice_notifier(&packet_netdev_notifier);
+out_pernet:
+ unregister_pernet_subsys(&packet_net_ops);
out:
return rc;
}
--
2.25.1

2022-09-21 12:18:17

by patchwork-bot+netdevbpf

Subject: Re: [PATCH net-next] net/af_packet: registration process optimization in packet_init()

Hello:

This patch was applied to netdev/net-next.git (master)
by David S. Miller <[email protected]>:

On Thu, 15 Sep 2022 09:08:35 +0800 you wrote:
> Now, register_pernet_subsys() and register_netdevice_notifier() are both
> after sock_register(). It can create PF_PACKET socket and process socket
> once sock_register() successfully. It is possible PF_PACKET socket is
> creating but register_pernet_subsys() and register_netdevice_notifier()
> are not registered yet. Thus net->packet.sklist_lock and net->packet.sklist
> will be accessed without initialization that is done in packet_net_init().
> Although this is a low probability scenario.
>
> [...]

Here is the summary with links:
- [net-next] net/af_packet: registration process optimization in packet_init()
https://git.kernel.org/netdev/net-next/c/63b7c2ebcc1d

You are awesome, thank you!
--
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