USB: quatech2: fix use-after-free in TIOCMIWAIT

commit 69f87f40d2b98e8b4ab82a121fd2bd584690b887 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>

diff --git a/drivers/usb/serial/quatech2.c b/drivers/usb/serial/quatech2.c
index a8d5110d4cc566369ebc6f47a2d99c023ef5e5a2..9f34c99e2d79a792b3a807fb0e0eb70ed4376956 100644 (file)
--- a/drivers/usb/serial/quatech2.c
+++ b/drivers/usb/serial/quatech2.c
@@ -128,7 +128,6 @@ struct qt2_port_private {
        u8          shadowLSR;
        u8          shadowMSR;
 
-       wait_queue_head_t   delta_msr_wait; /* Used for TIOCMIWAIT */
        struct async_icount icount;
 
        struct usb_serial_port *port;
@@ -506,8 +505,9 @@ 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->delta_msr_wait,
-                                        ((priv->icount.rng != prev.rng) ||
+               wait_event_interruptible(port->delta_msr_wait,
+                                        (port->serial->disconnected ||
+                                         (priv->icount.rng != prev.rng) ||
                                          (priv->icount.dsr != prev.dsr) ||
                                          (priv->icount.dcd != prev.dcd) ||
                                          (priv->icount.cts != prev.cts)));
@@ -515,6 +515,9 @@ static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
                if (signal_pending(current))
                        return -ERESTARTSYS;
 
+               if (port->serial->disconnected)
+                       return -EIO;
+
                spin_lock_irqsave(&priv->lock, flags);
                cur = priv->icount;
                spin_unlock_irqrestore(&priv->lock, flags);
@@ -841,7 +844,6 @@ static int qt2_port_probe(struct usb_serial_port *port)
 
        spin_lock_init(&port_priv->lock);
        spin_lock_init(&port_priv->urb_lock);
-       init_waitqueue_head(&port_priv->delta_msr_wait);
        port_priv->port = port;
 
        port_priv->write_urb = usb_alloc_urb(0, GFP_KERNEL);
@@ -984,7 +986,7 @@ static void qt2_update_msr(struct usb_serial_port *port, unsigned char *ch)
                if (newMSR & UART_MSR_TERI)
                        port_priv->icount.rng++;
 
-               wake_up_interruptible(&port_priv->delta_msr_wait);
+               wake_up_interruptible(&port->delta_msr_wait);
        }
 }