CVE-2026-31723

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

usb: gadget: fsubset: Fix netdevice lifecycle with device_move

The netdevice is allocated during function instance creation and registered during the bind phase with the gadget device as its sysfs parent. When the function unbinds, the parent device is destroyed, but the netdevice survives, resulting in dangling sysfs symlinks:

console:/ # ls -l /sys/class/net/usb0 lrwxrwxrwx ... /sys/class/net/usb0 -> /sys/devices/platform/.../gadget.0/net/usb0 console:/ # ls -l /sys/devices/platform/.../gadget.0/net/usb0 ls: .../gadget.0/net/usb0: No such file or directory

Use devicemove() to reparent the netdevice between the gadget device tree and /sys/devices/virtual across bind and unbind cycles. During the final unbind, calling devicemove(NULL) moves the netdevice to the virtual device tree before the gadget device is destroyed. On rebinding, device_move() reparents the device back under the new gadget, ensuring proper sysfs topology and power management ordering.

To maintain compatibility with legacy composite drivers (e.g., multi.c), the bound flag is used to indicate whether the network device is shared and pre-registered during the legacy driver's bind phase.