usb: gadget: f_hid: fix f_hidg lifetime vs cdev

Vulnerability Description

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.

References

• https://git.kernel.org/stable/c/1cd7f156f6389918f760687fbbf133c86da93162
• https://git.kernel.org/stable/c/c78c87c4e389b62f8892af7f59857447aa6d9797
• https://git.kernel.org/stable/c/1b6a53e447ec3d81623610c8c7ec5082b47dfdce
• https://git.kernel.org/stable/c/d3136b79705c2e3bba9c76adc5628af0215d798e
• https://git.kernel.org/stable/c/9e4b85d815b14bd4db2deea2a54264a23de8b896
• https://git.kernel.org/stable/c/9e08b7f5fa00e9d550851352bd0d1ba74ccffef2
• https://git.kernel.org/stable/c/89ff3dfac604614287ad5aad9370c3f984ea3f4b