diff --git a/sound/usb/midi2.c b/sound/usb/midi2.c
index 2785600d2312..04aeb9052f13 100644
--- a/sound/usb/midi2.c
+++ b/sound/usb/midi2.c
@@ -496,15 +496,17 @@ static void *find_usb_ms_endpoint_descriptor(struct usb_host_endpoint *hostep,
 	while (extralen > 3) {
 		struct usb_ms_endpoint_descriptor *ms_ep =
 			(struct usb_ms_endpoint_descriptor *)extra;
+		int length = ms_ep->bLength;
 
-		if (ms_ep->bLength > 3 &&
+		if (!length || length > extralen)
+			break;
+
+		if (length > 3 &&
 		    ms_ep->bDescriptorType == USB_DT_CS_ENDPOINT &&
 		    ms_ep->bDescriptorSubtype == subtype)
 			return ms_ep;
-		if (!extra[0])
-			break;
-		extralen -= extra[0];
-		extra += extra[0];
+		extralen -= length;
+		extra += length;
 	}
 	return NULL;
 }