releases/4.4.300/can-gs_usb-fix-use-of-uninitialized-variable-detach-device-on-reception-of-invalid-usb-data.patch

From 4a8737ff068724f509d583fef404d349adba80d6 Mon Sep 17 00:00:00 2001
From: Marc Kleine-Budde <mkl@pengutronix.de>
Date: Fri, 10 Dec 2021 10:03:09 +0100
Subject: can: gs_usb: fix use of uninitialized variable, detach device on reception of invalid USB data

From: Marc Kleine-Budde <mkl@pengutronix.de>

commit 4a8737ff068724f509d583fef404d349adba80d6 upstream.

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: d08e973a77d1 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/can/usb/gs_usb.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -303,7 +303,7 @@ static void gs_usb_receive_bulk_callback
 
 	/* device reports out of range channel id */
 	if (hf->channel >= GS_MAX_INTF)
-		goto resubmit_urb;
+		goto device_detach;
 
 	dev = usbcan->canch[hf->channel];
 
@@ -388,6 +388,7 @@ static void gs_usb_receive_bulk_callback
 
 	/* 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);