This is a note to let you know that I've just added the patch titled

serdev: ttyport: fix NULL-deref on hangup

to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 8bcd4e6a8decac251d55c4377e2e67f052777ce0 Mon Sep 17 00:00:00 2001

From: Johan Hovold johan@kernel.org Date: Fri, 3 Nov 2017 15:30:55 +0100 Subject: serdev: ttyport: fix NULL-deref on hangup

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") Cc: stable stable@vger.kernel.org # 4.11 Signed-off-by: Johan Hovold johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 09fbdd52a561..12cb9139073e 100644 --- a/drivers/tty/serdev/serdev-ttyport.c +++ b/drivers/tty/serdev/serdev-ttyport.c @@ -49,12 +49,19 @@ 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 = {