[ 095/104] USB: pl2303: 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 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@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/usb/serial/pl2303.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -150,7 +150,6 @@ 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;
@@ -204,7 +203,6 @@ static int pl2303_startup(struct usb_ser
 		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);
 	}
@@ -599,11 +597,14 @@ static int wait_modem_info(struct usb_se
 	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);
@@ -725,7 +726,7 @@ static void pl2303_update_line_status(st
 	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)
@@ -792,7 +793,7 @@ static void pl2303_process_read_urb(stru
 	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;


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