USB: spcp8x5: fix use-after-free in TIOCMIWAIT

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@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/serial/spcp8x5.c b/drivers/usb/serial/spcp8x5.c
index 180ea6c7911ce4348adc8f06b30d6fee9d4ae282..ba6b43850a5b3f4d28c35700d98975cb2fb3701b 100644 (file)
--- 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_serial *serial)
                        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(struct urb *urb)
        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(struct usb_serial_port *port,
 
        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);