--- 4895f0e053229bc8c04b568912340ffdbc02a076
+++ e3d4eda93ed95f915e186a2caaa7e48bf1524e6f
@@ -258,9 +258,16 @@ static int hci_uart_tty_open(struct tty_
 
 	BT_DBG("tty %p", tty);
 
+	/* FIXME: This btw is bogus, nothing requires the old ldisc to clear
+	   the pointer */
 	if (hu)
 		return -EEXIST;
 
+	/* Error if the tty has no write op instead of leaving an exploitable
+	   hole */
+	if (tty->ops->write == NULL)
+		return -EOPNOTSUPP;
+
 	if (!(hu = kzalloc(sizeof(struct hci_uart), GFP_KERNEL))) {
 		BT_ERR("Can't allocate control structure");
 		return -ENFILE;