CVE-2023-53580

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

USB: Gadget: core: Help prevent panic during UVC unconfigure

Avichal Rakesh reported a kernel panic that occurred when the UVC

gadget driver was removed from a gadget's configuration. The panic

involves a somewhat complicated interaction between the kernel driver

and a userspace component (as described in the Link tag below), but

the analysis did make one thing clear: The Gadget core should

accomodate gadget drivers calling usb_gadget_deactivate() as part of

their unbind procedure.

Currently this doesn't work. gadget_unbind_driver() calls

driver->unbind() while holding the udc->connect_lock mutex, and

usb_gadget_deactivate() attempts to acquire that mutex, which will

result in a deadlock.

The simple fix is for gadget_unbind_driver() to release the mutex when

invoking the ->unbind() callback. There is no particular reason for

it to be holding the mutex at that time, and the mutex isn't held

while the ->bind() callback is invoked. So we'll drop the mutex

before performing the unbind callback and reacquire it afterward.

We'll also add a couple of comments to usb_gadget_activate() and

usb_gadget_deactivate(). Because they run in process context they

must not be called from a gadget driver's ->disconnect() callback,

which (according to the kerneldoc for struct usb_gadget_driver in

include/linux/usb/gadget.h) may run in interrupt context. This may

help prevent similar bugs from arising in the future.