usb_ep_get and usb_handle_packet can deal with a NULL device, but we have to avoid dereferencing NULL pointers when building the id. Thanks to Gonglei for an initial stab at fixing this. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Read the documentation in qemu-doc.html or on http://wiki.qemu-project.org - QEMU team