[PATCH 047/102] USB: pl2303: fix use-after-free in TIOCMIWAIT

[Luis Henriques]

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

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

From: Johan Hovold <jhovold at gmail.com>

commit 40509ca982c00c4b70fc00be887509feca0bff15 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/pl2303.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 13b8dd6..6fe8d0e 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -137,7 +137,6 @@ enum pl2303_type {
 
 struct pl2303_private {
 	spinlock_t lock;
-	wait_queue_head_t delta_msr_wait;
 	u8 line_control;
 	u8 line_status;
 	enum pl2303_type type;
@@ -193,7 +192,6 @@ static int pl2303_startup(struct usb_serial *serial)
 		if (!priv)
 			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);
 	}
@@ -582,11 +580,14 @@ static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 	spin_unlock_irqrestore(&priv->lock, flags);
 
 	while (1) {
-		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);
@@ -705,7 +706,7 @@ static void pl2303_update_line_status(struct usb_serial_port *port,
 	spin_unlock_irqrestore(&priv->lock, flags);
 	if (priv->line_status & UART_BREAK_ERROR)
 		usb_serial_handle_break(port);
-	wake_up_interruptible(&priv->delta_msr_wait);
+	wake_up_interruptible(&port->delta_msr_wait);
 
 	tty = tty_port_tty_get(&port->port);
 	if (!tty)
@@ -770,7 +771,7 @@ static void pl2303_process_read_urb(struct urb *urb)
 	line_status = priv->line_status;
 	priv->line_status &= ~UART_STATE_TRANSIENT_MASK;
 	spin_unlock_irqrestore(&priv->lock, flags);
-	wake_up_interruptible(&priv->delta_msr_wait);
+	wake_up_interruptible(&port->delta_msr_wait);
 
 	if (!urb->actual_length)
 		return;
-- 
1.8.1.2