🛡️ CVE-2022-50568 — kernel

usb: gadget: f_hid: fix f_hidg lifetime vs cdev

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

usb: gadget: f_hid: fix f_hidg lifetime vs cdev

The embedded struct cdev does not have its lifetime correctly tied to

the enclosing struct f_hidg, so there is a use-after-free if /dev/hidgN

is held open while the gadget is deleted.

This can readily be replicated with libusbgx's example programs (for

conciseness - operating directly via configfs is equivalent):

gadget-hid

exec 3<> /dev/hidg0

gadget-vid-pid-remove

exec 3<&-

Pull the existing device up in to struct f_hidg and make use of the

cdev_device_{add,del}() helpers. This changes the lifetime of the

device object to match struct f_hidg, but note that it is still added

and deleted at the same time.