can: gs_usb: fix use of uninitialized variable, detach device on reception of invalid USB data

The received data contains the channel the received data is associated
with. If the channel number is bigger than the actual number of
channels assume broken or malicious USB device and shut it down.

This fixes the error found by clang:

| drivers/net/can/usb/gs_usb.c:386:6: error: variable 'dev' is used
|                                     uninitialized whenever 'if' condition is true
|         if (hf->channel >= GS_MAX_INTF)
|             ^~~~~~~~~~~~~~~~~~~~~~~~~~
| drivers/net/can/usb/gs_usb.c:474:10: note: uninitialized use occurs here
|                           hf, dev->gs_hf_size, gs_usb_receive_bulk_callback,
|                               ^~~

Link: https://lore.kernel.org/all/20211210091158.408326-1-mkl@pengutronix.de


Fixes: d08e973a ("can: gs_usb: Added support for the GS_USB CAN devices")
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/usb/gs_usb.c

@@ -321,7 +321,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 
 	/* device reports out of range channel id */
 	if (hf->channel >= GS_MAX_INTF)
-		goto resubmit_urb;
+		goto device_detach;
 
 	dev = usbcan->canch[hf->channel];
 
@@ -406,6 +406,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 
 	/* USB failure take down all interfaces */
 	if (rc == -ENODEV) {
+ device_detach:
 		for (rc = 0; rc < GS_MAX_INTF; rc++) {
 			if (usbcan->canch[rc])
 				netif_device_detach(usbcan->canch[rc]->netdev);