usb: gadget: prevent a ternary sign expansion bug

The problem is that "req->actual" is a u32, "req->status" is an int, and iocb->ki_complete() takes a long. We would expect that a negative error code in "req->status" would translate to a negative long value.

But what actually happens is that because "req->actual" is a u32, the error codes is type promoted to a high positive value and then remains a positive value when it is cast to long. (No sign expansion).

We can fix this by casting "req->status" to long.

---
 drivers/usb/gadget/legacy/inode.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index 71e7d10dd76b..cd8e2737947b 100644
@@ -498,7 +498,8 @@ static void ep_aio_complete(struct usb_ep *ep, struct usb_request *req)
 		iocb->private = NULL;
 		/* aio_complete() reports bytes-transferred _and_ faults */
 
-		iocb->ki_complete(iocb, req->actual ? req->actual : req->status,
+		iocb->ki_complete(iocb,
+				req->actual ? req->actual : (long)req->status,
 				req->status);
 	} else {
 		/* ep_copy_to_user() won't report both; we hide some faults */

2.30.2

I'm just going to assume your type promotion rank is correct :-)

balbi