CVE-2026-31723

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

usb: gadget: f_subset: Fix net_device lifecycle with device_move

The net_device 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 net_device 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 device_move() to reparent the net_device between the gadget device

tree and /sys/devices/virtual across bind and unbind cycles. During the

final unbind, calling device_move(NULL) moves the net_device 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.