usb: gadget: bdc: remove usage of list iterator past the loop body

If the list representing the request queue does not contain the expected
request, the value of the list_for_each_entry() iterator will not point
to a valid structure. To avoid type confusion in such case, the list
iterator scope will be limited to the list_for_each_entry() loop.

In preparation to limiting scope of the list iterator to the list traversal
loop, use a dedicated pointer to point to the found request object [1].

Link: https://lore.kernel.org/all/[e-mail]/
Signed-off-by: Jakob Koschel <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/gadget/udc/bdc/bdc_ep.c

···
 				  struct usb_request *_req)
 {
 	struct bdc_req *req;
+	struct bdc_req *iter;
 	unsigned long flags;
 	struct bdc_ep *ep;
 	struct bdc *bdc;
···
 	dev_dbg(bdc->dev, "%s ep:%s req:%p\n", __func__, ep->name, req);
 	bdc_dbg_bd_list(bdc, ep);
 	spin_lock_irqsave(&bdc->lock, flags);
+
+	req = NULL;
 	/* make sure it's still queued on this endpoint */
-	list_for_each_entry(req, &ep->queue, queue) {
-		if (&req->usb_req == _req)
-			break;
+	list_for_each_entry(iter, &ep->queue, queue) {
+		if (&iter->usb_req != _req)
+			continue;
+		req = iter;
+		break;
 	}
-	if (&req->usb_req != _req) {
+	if (!req) {
 		spin_unlock_irqrestore(&bdc->lock, flags);
 		dev_err(bdc->dev, "usb_req !=req n");
 		return -EINVAL;