From: Mahesh Bandewar <maheshb@google.com>
Date: Wed, 16 Nov 2022 01:19:14 +0000 (-0800)
Subject: ipvlan: hold lower dev to avoid possible use-after-free
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=40b9d1ab63f5c4f3cb69450044d07b45e5af72e1;p=linux.git

ipvlan: hold lower dev to avoid possible use-after-free

Recently syzkaller discovered the issue of disappearing lower
device (NETDEV_UNREGISTER) while the virtual device (like
macvlan) is still having it as a lower device. So it's just
a matter of time similar discovery will be made for IPvlan
device setup. So fixing it preemptively. Also while at it,
add a refcount tracker.

Fixes: 2ad7bf363841 ("ipvlan: Initial check-in of the IPVLAN driver.")
Signed-off-by: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/drivers/net/ipvlan/ipvlan.h b/drivers/net/ipvlan/ipvlan.h
index de94921cbef9f..025e0c19ec255 100644
--- a/drivers/net/ipvlan/ipvlan.h
+++ b/drivers/net/ipvlan/ipvlan.h
@@ -98,6 +98,7 @@ struct ipvl_port {
 	struct sk_buff_head	backlog;
 	int			count;
 	struct ida		ida;
+	netdevice_tracker	dev_tracker;
 };
 
 struct ipvl_skb_cb {
diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index 54c94a69c2bb8..796a38f9d7b24 100644
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -83,6 +83,7 @@ static int ipvlan_port_create(struct net_device *dev)
 	if (err)
 		goto err;
 
+	netdev_hold(dev, &port->dev_tracker, GFP_KERNEL);
 	return 0;
 
 err:
@@ -95,6 +96,7 @@ static void ipvlan_port_destroy(struct net_device *dev)
 	struct ipvl_port *port = ipvlan_port_get_rtnl(dev);
 	struct sk_buff *skb;
 
+	netdev_put(dev, &port->dev_tracker);
 	if (port->mode == IPVLAN_MODE_L3S)
 		ipvlan_l3s_unregister(port);
 	netdev_rx_handler_unregister(dev);