can: gs_usb: gs_usb_receive_bulk_callback(): check actual_length before accessing data

In the Linux kernel, the following vulnerability has been resolved: can: gs_usb: gs_usb_receive_bulk_callback(): check actual_length before accessing data The URB received in gs_usb_receive_bulk_callback() contains a struct gs_host_frame. The length of the data after the header depends on the gs_host_frame hf::flags and the active device features (e.g. time stamping). Introduce a new function gs_usb_get_minimum_length() and check that we have at least received the required amount of data before accessing it. Only copy the data to that skb that has actually been received. [mkl: rename gs_usb_get_minimum_length() -> +gs_usb_get_minimum_rx_length()]