usb/core/devio.c: Check for printer class specific request

commit 393cbb51 upstream.

In the usb printer class specific request get_device_id the value of
wIndex is (interface << 8 | altsetting) instead of just interface.
This enables the detection of some printers with libusb.
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Matthias Dellweg <2500@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/devio.c

@@ -607,9 +607,10 @@ static int findintfep(struct usb_device *dev, unsigned int ep)
 }
 
 static int check_ctrlrecip(struct dev_state *ps, unsigned int requesttype,
-			   unsigned int index)
+			   unsigned int request, unsigned int index)
 {
 	int ret = 0;
+	struct usb_host_interface *alt_setting;
 
 	if (ps->dev->state != USB_STATE_UNAUTHENTICATED
 	 && ps->dev->state != USB_STATE_ADDRESS
@@ -618,6 +619,19 @@ static int check_ctrlrecip(struct dev_state *ps, unsigned int requesttype,
 	if (USB_TYPE_VENDOR == (USB_TYPE_MASK & requesttype))
 		return 0;
 
+	/*
+	 * check for the special corner case 'get_device_id' in the printer
+	 * class specification, where wIndex is (interface << 8 | altsetting)
+	 * instead of just interface
+	 */
+	if (requesttype == 0xa1 && request == 0) {
+		alt_setting = usb_find_alt_setting(ps->dev->actconfig,
+						   index >> 8, index & 0xff);
+		if (alt_setting
+		 && alt_setting->desc.bInterfaceClass == USB_CLASS_PRINTER)
+			index >>= 8;
+	}
+
 	index &= 0xff;
 	switch (requesttype & USB_RECIP_MASK) {
 	case USB_RECIP_ENDPOINT:
@@ -770,7 +784,8 @@ static int proc_control(struct dev_state *ps, void __user *arg)
 
 	if (copy_from_user(&ctrl, arg, sizeof(ctrl)))
 		return -EFAULT;
-	ret = check_ctrlrecip(ps, ctrl.bRequestType, ctrl.wIndex);
+	ret = check_ctrlrecip(ps, ctrl.bRequestType, ctrl.bRequest,
+			      ctrl.wIndex);
 	if (ret)
 		return ret;
 	wLength = ctrl.wLength;		/* To suppress 64k PAGE_SIZE warning */
@@ -1100,7 +1115,7 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 			kfree(dr);
 			return -EINVAL;
 		}
-		ret = check_ctrlrecip(ps, dr->bRequestType,
+		ret = check_ctrlrecip(ps, dr->bRequestType, dr->bRequest,
 				      le16_to_cpup(&dr->wIndex));
 		if (ret) {
 			kfree(dr);