Merge branch 'gtp-pfcp-fix-use-after-free-of-udp-tunnel-socket'

Kuniyuki Iwashima says:

====================
gtp/pfcp: Fix use-after-free of UDP tunnel socket.

Xiao Liang pointed out weird netns usages in ->newlink() of
gtp and pfcp.

This series fixes the issues.

Link: https://lore.kernel.org/netdev/20250104125732.17335-1-shaw.leon@gmail.com/

Changes:
  v2:
    * Patch 1
      * Fix uninit/unused local var

  v1: https://lore.kernel.org/netdev/20250108062834.11117-1-kuniyu@amazon.com/
====================

Link: https://patch.msgid.link/20250110014754.33847-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/gtp.c

@@ -1524,8 +1524,8 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 		goto out_encap;
 	}
 
-	gn = net_generic(dev_net(dev), gtp_net_id);
-	list_add_rcu(&gtp->list, &gn->gtp_dev_list);
+	gn = net_generic(src_net, gtp_net_id);
+	list_add(&gtp->list, &gn->gtp_dev_list);
 	dev->priv_destructor = gtp_destructor;
 
 	netdev_dbg(dev, "registered new GTP interface\n");
@@ -1551,7 +1551,7 @@ static void gtp_dellink(struct net_device *dev, struct list_head *head)
 		hlist_for_each_entry_safe(pctx, next, &gtp->tid_hash[i], hlist_tid)
 			pdp_context_delete(pctx);
 
-	list_del_rcu(&gtp->list);
+	list_del(&gtp->list);
 	unregister_netdevice_queue(dev, head);
 }
 
@@ -2271,16 +2271,19 @@ static int gtp_genl_dump_pdp(struct sk_buff *skb,
 	struct gtp_dev *last_gtp = (struct gtp_dev *)cb->args[2], *gtp;
 	int i, j, bucket = cb->args[0], skip = cb->args[1];
 	struct net *net = sock_net(skb->sk);
+	struct net_device *dev;
 	struct pdp_ctx *pctx;
-	struct gtp_net *gn;
-
-	gn = net_generic(net, gtp_net_id);
 
 	if (cb->args[4])
 		return 0;
 
 	rcu_read_lock();
-	list_for_each_entry_rcu(gtp, &gn->gtp_dev_list, list) {
+	for_each_netdev_rcu(net, dev) {
+		if (dev->rtnl_link_ops != &gtp_link_ops)
+			continue;
+
+		gtp = netdev_priv(dev);
+
 		if (last_gtp && last_gtp != gtp)
 			continue;
 		else
@@ -2475,9 +2478,14 @@ static void __net_exit gtp_net_exit_batch_rtnl(struct list_head *net_list,
 
 	list_for_each_entry(net, net_list, exit_list) {
 		struct gtp_net *gn = net_generic(net, gtp_net_id);
-		struct gtp_dev *gtp;
+		struct gtp_dev *gtp, *gtp_next;
+		struct net_device *dev;
+
+		for_each_netdev(net, dev)
+			if (dev->rtnl_link_ops == &gtp_link_ops)
+				gtp_dellink(dev, dev_to_kill);
 
-		list_for_each_entry(gtp, &gn->gtp_dev_list, list)
+		list_for_each_entry_safe(gtp, gtp_next, &gn->gtp_dev_list, list)
 			gtp_dellink(gtp->dev, dev_to_kill);
 	}
 }

drivers/net/pfcp.c

@@ -206,8 +206,8 @@ static int pfcp_newlink(struct net *net, struct net_device *dev,
 		goto exit_del_pfcp_sock;
 	}
 
-	pn = net_generic(dev_net(dev), pfcp_net_id);
-	list_add_rcu(&pfcp->list, &pn->pfcp_dev_list);
+	pn = net_generic(net, pfcp_net_id);
+	list_add(&pfcp->list, &pn->pfcp_dev_list);
 
 	netdev_dbg(dev, "registered new PFCP interface\n");
 
@@ -224,7 +224,7 @@ static void pfcp_dellink(struct net_device *dev, struct list_head *head)
 {
 	struct pfcp_dev *pfcp = netdev_priv(dev);
 
-	list_del_rcu(&pfcp->list);
+	list_del(&pfcp->list);
 	unregister_netdevice_queue(dev, head);
 }
 
@@ -247,11 +247,16 @@ static int __net_init pfcp_net_init(struct net *net)
 static void __net_exit pfcp_net_exit(struct net *net)
 {
 	struct pfcp_net *pn = net_generic(net, pfcp_net_id);
-	struct pfcp_dev *pfcp;
+	struct pfcp_dev *pfcp, *pfcp_next;
+	struct net_device *dev;
 	LIST_HEAD(list);
 
 	rtnl_lock();
-	list_for_each_entry(pfcp, &pn->pfcp_dev_list, list)
+	for_each_netdev(net, dev)
+		if (dev->rtnl_link_ops == &pfcp_link_ops)
+			pfcp_dellink(dev, &list);
+
+	list_for_each_entry_safe(pfcp, pfcp_next, &pn->pfcp_dev_list, list)
 		pfcp_dellink(pfcp->dev, &list);
 
 	unregister_netdevice_many(&list);