USB: ehci: paranoia, reject large control transfers

Some EHCI fault paths with large control transfers aren't coded.  Avoid
problems by rejecting transfers that may need two qTDs (16+ KB).  This is
mostly paranoia; even 4 KB transfers are rare, and most HCDs use lower
limits (so it's unlikely anyone would ever try such a thing).
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/ehci-hcd.c

@@ -764,8 +764,14 @@ static int ehci_urb_enqueue (
 	INIT_LIST_HEAD (&qtd_list);
 
 	switch (usb_pipetype (urb->pipe)) {
-	// case PIPE_CONTROL:
-	// case PIPE_BULK:
+	case PIPE_CONTROL:
+		/* qh_completions() code doesn't handle all the fault cases
+		 * in multi-TD control transfers.  Even 1KB is rare anyway.
+		 */
+		if (urb->transfer_buffer_length > (16 * 1024))
+			return -EMSGSIZE;
+		/* FALLTHROUGH */
+	/* case PIPE_BULK: */
 	default:
 		if (!qh_urb_transaction (ehci, urb, &qtd_list, mem_flags))
 			return -ENOMEM;