CVE-2026-31502

In the Linux kernel, the following vulnerability has been resolved:

team: fix header_ops type confusion with non-Ethernet ports

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.