team: fix header_ops type confusion with non-Ethernet ports

Similar to commit 950803f ("bonding: fix type confusion in
bond_setup_by_slave()") team has the same class of header_ops type
confusion.

For non-Ethernet ports, team_setup_by_port() copies port_dev->header_ops
directly. When the team device later calls dev_hard_header() or
dev_parse_header(), these callbacks can run with the team net_device
instead of the real lower device, so netdev_priv(dev) is interpreted as
the wrong private type and can crash.

The syzbot report shows a crash in bond_header_create(), but the root
cause is in team: the topology is gre -> bond -> team, and team calls
the inherited header_ops with its own net_device instead of the lower
device, so bond_header_create() receives a team device and interprets
netdev_priv() as bonding private data, causing a type confusion crash.

Fix this by introducing team header_ops wrappers for create/parse,
selecting a team port under RCU, and calling the lower device callbacks
with port->dev, so each callback always sees the correct net_device
context.

Also pass the selected lower device to the lower parse callback, so
recursion is bounded in stacked non-Ethernet topologies and parse
callbacks always run with the correct device context.

Fixes: 1d76efe ("team: add support for non-ethernet devices")
Reported-by: [email protected]
Closes: https://lore.kernel.org/all/[email protected]/T/
Cc: Jiayuan Chen <[email protected]>
Signed-off-by: Jiayuan Chen <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

Author: mrpre

drivers/net/team/team_core.c

@@ -2058,6 +2058,68 @@ static const struct ethtool_ops team_ethtool_ops = {
  * rt netlink interface
  ***********************/
 
+/* For tx path we need a linkup && enabled port and for parse any port
+ * suffices.
+ */
+static struct team_port *team_header_port_get_rcu(struct team *team,
+						  bool txable)
+{
+	struct team_port *port;
+
+	list_for_each_entry_rcu(port, &team->port_list, list) {
+		if (!txable || team_port_txable(port))
+			return port;
+	}
+
+	return NULL;
+}
+
+static int team_header_create(struct sk_buff *skb, struct net_device *team_dev,
+			      unsigned short type, const void *daddr,
+			      const void *saddr, unsigned int len)
+{
+	struct team *team = netdev_priv(team_dev);
+	const struct header_ops *port_ops;
+	struct team_port *port;
+	int ret = 0;
+
+	rcu_read_lock();
+	port = team_header_port_get_rcu(team, true);
+	if (port) {
+		port_ops = READ_ONCE(port->dev->header_ops);
+		if (port_ops && port_ops->create)
+			ret = port_ops->create(skb, port->dev,
+					       type, daddr, saddr, len);
+	}
+	rcu_read_unlock();
+	return ret;
+}
+
+static int team_header_parse(const struct sk_buff *skb,
+			     const struct net_device *team_dev,
+			     unsigned char *haddr)
+{
+	struct team *team = netdev_priv(team_dev);
+	const struct header_ops *port_ops;
+	struct team_port *port;
+	int ret = 0;
+
+	rcu_read_lock();
+	port = team_header_port_get_rcu(team, false);
+	if (port) {
+		port_ops = READ_ONCE(port->dev->header_ops);
+		if (port_ops && port_ops->parse)
+			ret = port_ops->parse(skb, port->dev, haddr);
+	}
+	rcu_read_unlock();
+	return ret;
+}
+
+static const struct header_ops team_header_ops = {
+	.create		= team_header_create,
+	.parse		= team_header_parse,
+};
+
 static void team_setup_by_port(struct net_device *dev,
 			       struct net_device *port_dev)
 {
@@ -2066,7 +2128,8 @@ static void team_setup_by_port(struct net_device *dev,
 	if (port_dev->type == ARPHRD_ETHER)
 		dev->header_ops	= team->header_ops_cache;
 	else
-		dev->header_ops	= port_dev->header_ops;
+		dev->header_ops	= port_dev->header_ops ?
+				  &team_header_ops : NULL;
 	dev->type = port_dev->type;
 	dev->hard_header_len = port_dev->hard_header_len;
 	dev->needed_headroom = port_dev->needed_headroom;