Affected: Linux

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

net: usb: ipheth: fix carrier_work UAF on disconnect

ipheth_sndbulk_callback() re-arms the carrier-check work on any non-zero URB status:

else schedule_delayed_work(&dev->carrier_work, 0);

Nothing ties that to the interface being up, so the work can be armed again after ipheth_close() has already drained it, and stay armed until the netdev whose private area embeds it is freed.

On unplug with a TX URB in flight, ipheth_disconnect() drains the work through unregister_netdev() -> ipheth_close() -> cancel_delayed_work_sync() and only then calls ipheth_kill_urbs(). usb_kill_urb() completes the in-flight TX URB with -ENOENT, so ipheth_sndbulk_callback() runs after the drain and re-arms carrier_work.

The same completion also re-arms the work if the interface is only brought down while a TX URB is in flight, and ipheth_carrier_check_work() then keeps re-queueing itself once a second. unregister_netdev() does not call ipheth_close() for an already-down interface, so nothing drains it on the later unplug either.

In both cases free_netdev() frees the netdev while carrier_work is still pending, and ipheth_carrier_check_work() dereferences freed memory.

Tie the work to the interface state instead of chasing the completion: disable it in ipheth_close() and enable it in ipheth_open(), so a schedule_delayed_work() from the URB completion is a no-op whenever the interface is not up. disable_delayed_work_sync() al…