[PATCH 6.12 091/244] team: fix header_ops type confusion with non-Ethernet ports

Greg Kroah-Hartman
2026-03-31T16:50:00Z

From: Jiayuan Chen <jiayuan.chen@shopee.com>

[ Upstream commit 425000dbf17373a4ab8be9428f5dc055ef870a56 ]

Similar to commit 950803f72547 ("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: 1d76efe1577b ("team: add support for non-ethernet devices")
Reported-by: syzbot+3d8bc31c45e11450f24c@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/69b46af7.050a0220.36eb34.000e.GAE@google.com/T/
Cc: Jiayuan Chen <jiayuan.chen@linux.dev>
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Link: https://patch.msgid.link/20260320072139.134249-2-jiayuan.chen@linux.dev
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/team/team_core.c | 65 +++++++++++++++++++++++++++++++++++-
1 file changed, 64 insertions(+), 1 deletion(-)

diff --git a/drivers/net/team/team_core.c b/drivers/net/team/team_core.c
index 50732f9699eea..3cbaee3ff5fd7 100644
--- a/drivers/net/team/team_core.c
+++ b/drivers/net/team/team_core.c
@@ -2133,6 +2133,68 @@ 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)
{
@@ -2141,7 +2203,8 @@ 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;
--
2.51.0