usb: gadget: s3c-hsudc: 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/
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Link: https://lore.kernel.org/r/20220308171818.384491-15-jakobkoschel@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/s3c-hsudc.c

@@ -877,7 +877,7 @@ static int s3c_hsudc_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 {
 	struct s3c_hsudc_ep *hsep = our_ep(_ep);
 	struct s3c_hsudc *hsudc = hsep->dev;
-	struct s3c_hsudc_req *hsreq;
+	struct s3c_hsudc_req *hsreq = NULL, *iter;
 	unsigned long flags;
 
 	hsep = our_ep(_ep);
@@ -886,11 +886,13 @@ static int s3c_hsudc_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 
 	spin_lock_irqsave(&hsudc->lock, flags);
 
-	list_for_each_entry(hsreq, &hsep->queue, queue) {
-		if (&hsreq->req == _req)
-			break;
+	list_for_each_entry(iter, &hsep->queue, queue) {
+		if (&iter->req != _req)
+			continue;
+		hsreq = iter;
+		break;
 	}
-	if (&hsreq->req != _req) {
+	if (!hsreq) {
 		spin_unlock_irqrestore(&hsudc->lock, flags);
 		return -EINVAL;
 	}