diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 0ad32888091c16c1c27de4c032517df583ea4c9f..c3954fbf6ac402d7d8e8a92389c4f1ecdc065e53 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1815,6 +1815,7 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
 			/* FIXME: does n_tty_set_room need locking ? */
 			n_tty_set_room(tty);
 			timeout = schedule_timeout(timeout);
+			BUG_ON(!tty->read_buf);
 			continue;
 		}
 		__set_current_state(TASK_RUNNING);