patch "serdev: fix tty-port client deregistration" added to tty-linus

[<gregkh@linuxfoundation.org>]

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

    serdev: fix tty-port client deregistration

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 aee5da7838787f8ed47f825dbe09e2812acdf97b Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Tue, 11 Apr 2017 19:07:29 +0200
Subject: serdev: fix tty-port client deregistration

The port client data must be set when registering the serdev controller
or client deregistration will fail (and the serdev devices are left
registered and allocated) if the port was never opened in between.

Make sure to clear the port client data on any probe errors to avoid a
use-after-free when the client is later deregistered unconditionally
(e.g. in a tty-port deregistration helper).

Also move port client operation initialisation to registration. Note
that the client ops must be restored on failed probe.

Fixes: bed35c6dfa6a ("serdev: add a tty port controller driver")
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serdev/serdev-ttyport.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c
index 487c88f6aa0e..013efffd2e82 100644
--- a/drivers/tty/serdev/serdev-ttyport.c
+++ b/drivers/tty/serdev/serdev-ttyport.c
@@ -102,9 +102,6 @@ static int ttyport_open(struct serdev_controller *ctrl)
 		return PTR_ERR(tty);
 	serport->tty = tty;
 
-	serport->port->client_ops = &client_ops;
-	serport->port->client_data = ctrl;
-
 	if (tty->ops->open)
 		tty->ops->open(serport->tty, NULL);
 	else
@@ -215,6 +212,7 @@ struct device *serdev_tty_port_register(struct tty_port *port,
 					struct device *parent,
 					struct tty_driver *drv, int idx)
 {
+	const struct tty_port_client_operations *old_ops;
 	struct serdev_controller *ctrl;
 	struct serport *serport;
 	int ret;
@@ -233,15 +231,22 @@ struct device *serdev_tty_port_register(struct tty_port *port,
 
 	ctrl->ops = &ctrl_ops;
 
+	old_ops = port->client_ops;
+	port->client_ops = &client_ops;
+	port->client_data = ctrl;
+
 	ret = serdev_controller_add(ctrl);
 	if (ret)
-		goto err_controller_put;
+		goto err_reset_data;
 
 	dev_info(&ctrl->dev, "tty port %s%d registered\n", drv->name, idx);
 	return &ctrl->dev;
 
-err_controller_put:
+err_reset_data:
+	port->client_data = NULL;
+	port->client_ops = old_ops;
 	serdev_controller_put(ctrl);
+
 	return ERR_PTR(ret);
 }
 
-- 
2.13.0