USB: iowarrior: fix use-after-free after driver unbind

BugLink: https://bugs.launchpad.net/bugs/1848780

commit b5f8d468 upstream.

Make sure to stop also the asynchronous write URBs on disconnect() to
avoid use-after-free in the completion handler after driver unbind.

Fixes: 946b960d ("USB: add driver for iowarrior devices.")
Cc: stable <stable@vger.kernel.org>	# 2.6.21: 51a2f077 ("USB: introduce usb_anchor")
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191009104846.5925-4-johan@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/usb/misc/iowarrior.c

@@ -89,6 +89,7 @@ struct iowarrior {
 	char chip_serial[9];		/* the serial number string of the chip connected */
 	int report_size;		/* number of bytes in a report */
 	u16 product_id;
+	struct usb_anchor submitted;
 };
 
 /*--------------*/
@@ -437,11 +438,13 @@ static ssize_t iowarrior_write(struct file *file,
 			retval = -EFAULT;
 			goto error;
 		}
+		usb_anchor_urb(int_out_urb, &dev->submitted);
 		retval = usb_submit_urb(int_out_urb, GFP_KERNEL);
 		if (retval) {
 			dev_dbg(&dev->interface->dev,
 				"submit error %d for urb nr.%d\n",
 				retval, atomic_read(&dev->write_busy));
+			usb_unanchor_urb(int_out_urb);
 			goto error;
 		}
 		/* submit was ok */
@@ -788,6 +791,8 @@ static int iowarrior_probe(struct usb_interface *interface,
 	iface_desc = interface->cur_altsetting;
 	dev->product_id = le16_to_cpu(udev->descriptor.idProduct);
 
+	init_usb_anchor(&dev->submitted);
+
 	/* set up the endpoint information */
 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 		endpoint = &iface_desc->endpoint[i].desc;
@@ -917,6 +922,7 @@ static void iowarrior_disconnect(struct usb_interface *interface)
 		   Deleting the device is postponed until close() was called.
 		 */
 		usb_kill_urb(dev->int_in_urb);
+		usb_kill_anchored_urbs(&dev->submitted);
 		wake_up_interruptible(&dev->read_wait);
 		wake_up_interruptible(&dev->write_wait);
 		mutex_unlock(&dev->mutex);