Handle broken union functional descriptors where the master-interface doesn't exist or where its class is of neither Communication or Data type (as required by the specification) by falling back to "combined-interface" probing. Note that this still allows for handling union descriptors with switched interfaces. This is specifically makes the Whistler radio scanners TRX series devices work with the driver without adding further quirks to the device-id table. Link: https://lore.kernel.org/r/5f4ca4f8.1c69fb81.a4487.0f5f@xxxxxxxxxxxxx Reported-by: Daniel Caujolle-Bert <f1rmb.daniel@xxxxxxxxx> Signed-off-by: Johan Hovold <johan@xxxxxxxxxx> --- drivers/usb/class/cdc-acm.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index e28ac640ff9c..5b1a1cd0168d 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1240,9 +1240,21 @@ static int acm_probe(struct usb_interface *intf, } } } else { + int class = -1; + data_intf_num = union_header->bSlaveInterface0; control_interface = usb_ifnum_to_if(usb_dev, union_header->bMasterInterface0); data_interface = usb_ifnum_to_if(usb_dev, data_intf_num); + + if (control_interface) + class = control_interface->cur_altsetting->desc.bInterfaceClass; + + if (class != USB_CLASS_COMM && class != USB_CLASS_CDC_DATA) { + dev_warn(&intf->dev, "Broken union descriptor, assuming single interface\n"); + combined_interfaces = 1; + control_interface = data_interface = intf; + goto look_for_collapsed_interface; + } } if (!control_interface || !data_interface) { -- 2.26.2
