[ovs-dev] [PATCH 3/3] lisp: avoid using stale lisp socket.

Joe Stringer joe at ovn.org
Mon Oct 31 21:11:15 UTC 2016


On 29 October 2016 at 21:33, Pravin B Shelar <pshelar at ovn.org> wrote:
> This patch is similar to earlier vxlan patch.
> Lisp device close operation frees lisp socket. This
> operation can race with lisp-xmit function which
> dereferences lisp socket. Following patch uses RCU
> mechanism to avoid this situation.
>
> Signed-off-by: Pravin B Shelar <pshelar at ovn.org>

Thanks, one style comment below. Otherwise:

Acked-by: Joe Stringer <joe at ovn.org>

> @@ -442,11 +449,13 @@ static int lisp_open(struct net_device *dev)
>         struct lisp_dev *lisp = netdev_priv(dev);
>         struct udp_tunnel_sock_cfg tunnel_cfg;
>         struct net *net = lisp->net;
> +       struct socket *sock;
>
> -       lisp->sock = create_sock(net, false, lisp->dst_port);
> -       if (IS_ERR(lisp->sock))
> -               return PTR_ERR(lisp->sock);
> +       sock = create_sock(net, false, lisp->dst_port);
> +       if (IS_ERR(sock))
> +               return PTR_ERR(sock);
>
> +       rcu_assign_pointer(lisp->sock, sock);
>         /* Mark socket as an encapsulation socket */
>         tunnel_cfg.sk_user_data = dev;
>         tunnel_cfg.encap_type = 1;

At the end of lisp_open(), we pass lisp->sock directly to another
function. I think it's ok, but you could remove all direct
dereferences of 'lisp->sock' if you rolled in this incremental patch:

diff --git a/datapath/linux/compat/lisp.c b/datapath/linux/compat/lisp.c
index 193196c7e328..15f851de9ff4 100644
--- a/datapath/linux/compat/lisp.c
+++ b/datapath/linux/compat/lisp.c
@@ -461,7 +461,7 @@ static int lisp_open(struct net_device *dev)
       tunnel_cfg.encap_type = 1;
       tunnel_cfg.encap_rcv = lisp_rcv;
       tunnel_cfg.encap_destroy = NULL;
-       setup_udp_tunnel_sock(net, lisp->sock, &tunnel_cfg);
+       setup_udp_tunnel_sock(net, sock, &tunnel_cfg);
       return 0;
}



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