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 gadgets 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 doesnt 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 isnt held while the ->bind() callback is invoked. So well drop the mutex before performing the unbind callback and reacquire it afterward.

Well 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 drivers ->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.

Affected Software

References

• https://git.kernel.org/stable/c/65dadb2beeb7360232b09ebc4585b54475dfee06
• https://git.kernel.org/stable/c/8c1edc00db65f6d4408b3d1cd845e8da3b9e0ca4
• https://git.kernel.org/stable/c/bed19d95fcb9c98dfaa9585922b39a2dfba7898d