[ 096/104] USB: spcp8x5: fix use-after-free in TIOCMIWAIT

[Ben Hutchings]

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <jhovold@xxxxxxxxx>

commit dbcea7615d8d7d58f6ff49d2c5568113f70effe9 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@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.2: adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/usb/serial/spcp8x5.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/drivers/usb/serial/spcp8x5.c
+++ b/drivers/usb/serial/spcp8x5.c
@@ -163,7 +163,6 @@ static struct usb_driver spcp8x5_driver
 struct spcp8x5_private {
 	spinlock_t 	lock;
 	enum spcp8x5_type	type;
-	wait_queue_head_t	delta_msr_wait;
 	u8 			line_control;
 	u8 			line_status;
 };
@@ -197,7 +196,6 @@ static int spcp8x5_startup(struct usb_se
 			goto cleanup;
 
 		spin_lock_init(&priv->lock);
-		init_waitqueue_head(&priv->delta_msr_wait);
 		priv->type = type;
 		usb_set_serial_port_data(serial->port[i] , priv);
 	}
@@ -502,7 +500,7 @@ static void spcp8x5_process_read_urb(str
 	priv->line_status &= ~UART_STATE_TRANSIENT_MASK;
 	spin_unlock_irqrestore(&priv->lock, flags);
 	/* wake up the wait for termios */
-	wake_up_interruptible(&priv->delta_msr_wait);
+	wake_up_interruptible(&port->delta_msr_wait);
 
 	if (!urb->actual_length)
 		return;
@@ -552,12 +550,15 @@ static int spcp8x5_wait_modem_info(struc
 
 	while (1) {
 		/* wake up in bulk read */
-		interruptible_sleep_on(&priv->delta_msr_wait);
+		interruptible_sleep_on(&port->delta_msr_wait);
 
 		/* see if a signal did it */
 		if (signal_pending(current))
 			return -ERESTARTSYS;
 
+		if (port->serial->disconnected)
+			return -EIO;
+
 		spin_lock_irqsave(&priv->lock, flags);
 		status = priv->line_status;
 		spin_unlock_irqrestore(&priv->lock, flags);


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