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 bondsetupbyslave()") team has the same class of headerops type confusion.

For non-Ethernet ports, teamsetupbyport() copies portdev->headerops directly. When the team device later calls devhardheader() or devparseheader(), these callbacks can run with the team netdevice 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 bondheadercreate(), but the root cause is in team: the topology is gre -> bond -> team, and team calls the inherited headerops with its own netdevice instead of the lower device, so bondheadercreate() receives a team device and interprets netdev_priv() as bonding private data, causing a type confusion crash.

Fix this by introducing team headerops 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 netdevice 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.