[ 3.5.y.z extended stable ] Patch "USB: oti6858: fix use-after-free in TIOCMIWAIT" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    USB: oti6858: fix use-after-free in TIOCMIWAIT

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From add26c5b5d85dda97b790767bb812d23e58cf4c8 Mon Sep 17 00:00:00 2001
From: Johan Hovold <jhovold at gmail.com>
Date: Tue, 19 Mar 2013 09:21:21 +0100
Subject: [PATCH] USB: oti6858: fix use-after-free in TIOCMIWAIT

commit 8edfdab37157d2683e51b8be5d3d5697f66a9f7b upstream.

Use the port wait queue and make sure to check the serial disconnected
flag before accessing private port data after waking up.

This is is needed as the private port data (including the wait queue
itself) can be gone when waking up after a disconnect.

Signed-off-by: Johan Hovold <jhovold at gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
[ luis: backported to 3.5; adjust context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/usb/serial/oti6858.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/serial/oti6858.c b/drivers/usb/serial/oti6858.c
index 5976b65..d9c40b1 100644
--- a/drivers/usb/serial/oti6858.c
+++ b/drivers/usb/serial/oti6858.c
@@ -191,7 +191,6 @@ struct oti6858_private {
 	u8 setup_done;
 	struct delayed_work delayed_setup_work;

-	wait_queue_head_t intr_wait;
 	struct usb_serial_port *port;   /* USB port with which associated */
 };

@@ -345,7 +344,6 @@ static int oti6858_startup(struct usb_serial *serial)
 			break;

 		spin_lock_init(&priv->lock);
-		init_waitqueue_head(&priv->intr_wait);
 /*		INIT_WORK(&priv->setup_work, setup_line, serial->port[i]); */
 /*		INIT_WORK(&priv->write_work, send_data, serial->port[i]); */
 		priv->port = port;
@@ -672,11 +670,15 @@ static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 	spin_unlock_irqrestore(&priv->lock, flags);

 	while (1) {
-		wait_event_interruptible(priv->intr_wait,
+		wait_event_interruptible(port->delta_msr_wait,
+					port->serial->disconnected ||
 					priv->status.pin_state != prev);
 		if (signal_pending(current))
 			return -ERESTARTSYS;

+		if (port->serial->disconnected)
+			return -EIO;
+
 		spin_lock_irqsave(&priv->lock, flags);
 		status = priv->status.pin_state & PIN_MASK;
 		spin_unlock_irqrestore(&priv->lock, flags);
@@ -783,7 +785,7 @@ static void oti6858_read_int_callback(struct urb *urb)

 		if (!priv->transient) {
 			if (xs->pin_state != priv->status.pin_state)
-				wake_up_interruptible(&priv->intr_wait);
+				wake_up_interruptible(&port->delta_msr_wait);
 			memcpy(&priv->status, xs, OTI6858_CTRL_PKT_SIZE);
 		}

--
1.8.1.2