usb: gadget: goku_udc: 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/YhdfEIwI4EdtHdym@kroah.com/
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Link: https://lore.kernel.org/r/20220308171818.384491-7-jakobkoschel@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/goku_udc.c

@@ -809,7 +809,7 @@ static void nuke(struct goku_ep *ep, int status)
 /* dequeue JUST ONE request */
 static int goku_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 {
-	struct goku_request	*req;
+	struct goku_request	*req = NULL, *iter;
 	struct goku_ep		*ep;
 	struct goku_udc		*dev;
 	unsigned long		flags;
@@ -833,11 +833,13 @@ static int goku_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 	spin_lock_irqsave(&dev->lock, flags);
 
 	/* make sure it's actually queued on this endpoint */
-	list_for_each_entry (req, &ep->queue, queue) {
-		if (&req->req == _req)
-			break;
+	list_for_each_entry(iter, &ep->queue, queue) {
+		if (&iter->req != _req)
+			continue;
+		req = iter;
+		break;
 	}
-	if (&req->req != _req) {
+	if (!req) {
 		spin_unlock_irqrestore (&dev->lock, flags);
 		return -EINVAL;
 	}