diff --git a/drivers/usb/serial/keyspan.c b/drivers/usb/serial/keyspan.c
index 46448843541a..28b80607cebd 100644
--- a/drivers/usb/serial/keyspan.c
+++ b/drivers/usb/serial/keyspan.c
@@ -1187,6 +1187,10 @@ static void usa49wg_indat_callback(struct urb *urb)
 	len = 0;
 
 	while (i < urb->actual_length) {
+		if (urb->actual_length - i < 3) {
+			dev_warn_ratelimited(&urb->dev->dev, "malformed indat packet\n");
+			break;
+		}
 
 		/* Check port number from message */
 		if (data[i] >= serial->num_ports) {