From 5a3da8bd93c78b6a4aed19c83cb8f493dfc4dfef Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Fri, 3 Nov 2017 15:30:55 +0100 Subject: [PATCH] serdev: ttyport: fix NULL-deref on hangup commit 8bcd4e6a8decac251d55c4377e2e67f052777ce0 upstream. Make sure to use a properly refcounted tty_struct in write_wake up to avoid dereferencing a NULL-pointer when a port is being hung up. Fixes: bed35c6dfa6a ("serdev: add a tty port controller driver") Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serdev/serdev-ttyport.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c index d4efe43..ce7fc44 100644 --- a/drivers/tty/serdev/serdev-ttyport.c +++ b/drivers/tty/serdev/serdev-ttyport.c @@ -57,12 +57,19 @@ static void ttyport_write_wakeup(struct tty_port *port) { struct serdev_controller *ctrl = port->client_data; struct serport *serport = serdev_controller_get_drvdata(ctrl); + struct tty_struct *tty; + + tty = tty_port_tty_get(port); + if (!tty) + return; - if (test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &port->tty->flags) && + if (test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags) && test_bit(SERPORT_ACTIVE, &serport->flags)) serdev_controller_write_wakeup(ctrl); - wake_up_interruptible_poll(&port->tty->write_wait, POLLOUT); + wake_up_interruptible_poll(&tty->write_wait, POLLOUT); + + tty_kref_put(tty); } static const struct tty_port_client_operations client_ops = { -- 2.7.4