Commit message: can: gs_usb: Don't use stack memory for USB transfers

Fixes: 05ca5270005c can: gs_usb: add ethtool set_phys_id callback to locate physical device

The gs_usb driver is performing USB transfers using buffers allocated on
the stack. This causes the driver to not function with vmapped stacks.
Instead, allocate memory for the transfer buffers.

Signed-off-by: Ethan Zonca <e@ethanzonca.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v4.8
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
CVE: CVE-2017-8066
CWE: CWE-119
Vulnerability description: drivers/net/can/usb/gs_usb.c in the Linux kernel 4.9.x and 4.10.x before 4.10.2 interacts incorrectly with the CONFIG_VMAP_STACK option, which allows local users to cause a denial of service (system crash or memory corruption) or possibly have unspecified other impact by leveraging use of more than one virtual page for a DMA scatterlist.

Project: linux
File: gs_usb.c

static int gs_usb_probe(struct usb_interface *intf,
			const struct usb_device_id *id)
{
 	struct gs_usb *dev;
 	int rc = -ENOMEM;
 	unsigned int icount, i;
	struct gs_host_config *hconf;
	struct gs_device_config *dconf;

	hconf = kmalloc(sizeof(*hconf), GFP_KERNEL);
	if (!hconf)
		return -ENOMEM;

	hconf->byte_order = 0x0000beef;
 
 	/* send host config */
 	rc = usb_control_msg(interface_to_usbdev(intf),
			     usb_sndctrlpipe(interface_to_usbdev(intf), 0),
			     GS_USB_BREQ_HOST_FORMAT,
 			     USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
 			     1,
 			     intf->altsetting[0].desc.bInterfaceNumber,
			     hconf,
			     sizeof(*hconf),
 			     1000);
 
	kfree(hconf);

 	if (rc < 0) {
 		dev_err(&intf->dev, "Couldn't send data format (err=%d)\n",
 			rc);
 		return rc;
 	}
 
	dconf = kmalloc(sizeof(*dconf), GFP_KERNEL);
	if (!dconf)
		return -ENOMEM;

 	/* read device config */
 	rc = usb_control_msg(interface_to_usbdev(intf),
 			     usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
 			     GS_USB_BREQ_DEVICE_CONFIG,
 			     USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
 			     1,
 			     intf->altsetting[0].desc.bInterfaceNumber,
			     dconf,
			     sizeof(*dconf),
 			     1000);
 	if (rc < 0) {
 		dev_err(&intf->dev, "Couldn't get device config: (err=%d)\n",
 			rc);
		kfree(dconf);
 		return rc;
 	}
 
	icount = dconf->icount + 1;
 	dev_info(&intf->dev, "Configuring for %d interfaces\n", icount);
 
 	if (icount > GS_MAX_INTF) {
 		dev_err(&intf->dev,
 			"Driver cannot handle more that %d CAN interfaces\n",
 			GS_MAX_INTF);
		kfree(dconf);
 		return -EINVAL;
 	}
 
 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev) {
		kfree(dconf);
 		return -ENOMEM;
	}

 	init_usb_anchor(&dev->rx_submitted);
 
 	atomic_set(&dev->active_channels, 0);

	usb_set_intfdata(intf, dev);
 	dev->udev = interface_to_usbdev(intf);
 
 	for (i = 0; i < icount; i++) {
		dev->canch[i] = gs_make_candev(i, intf, dconf);
 		if (IS_ERR_OR_NULL(dev->canch[i])) {
 			/* save error code to return later */
 			rc = PTR_ERR(dev->canch[i]);

			/* on failure destroy previously created candevs */
			icount = i;
			for (i = 0; i < icount; i++)
 				gs_destroy_candev(dev->canch[i]);
 
 			usb_kill_anchored_urbs(&dev->rx_submitted);
			kfree(dconf);
 			kfree(dev);
 			return rc;
 		}
 		dev->canch[i]->parent = dev;
 	}
 
	kfree(dconf);

 	return 0;
 }