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

serdev: ttyport: fix NULL-deref on hangup

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: serdev-ttyport-fix-null-deref-on-hangup.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

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

From: Johan Hovold johan@kernel.org

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 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(-)

--- a/drivers/tty/serdev/serdev-ttyport.c +++ b/drivers/tty/serdev/serdev-ttyport.c @@ -57,12 +57,19 @@ static void ttyport_write_wakeup(struct { struct serdev_controller *ctrl = port->client_data; struct serport *serport = serdev_controller_get_drvdata(ctrl); + struct tty_struct *tty;

- if (test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &port->tty->flags) && + tty = tty_port_tty_get(port); + if (!tty) + return; + + 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 = {

Patches currently in stable-queue which might be from johan@kernel.org are

queue-4.14/serdev-ttyport-fix-null-deref-on-hangup.patch queue-4.14/serdev-ttyport-fix-tty-locking-in-close.patch queue-4.14/serdev-ttyport-add-missing-receive_buf-sanity-checks.patch