USB: ssu100: fix use-after-free in TIOCMIWAIT

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.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/serial/ssu100.c b/drivers/usb/serial/ssu100.c
index b57cf841c5b6aa2ab1c21e13c12e063d51a2a9e7..4b2a19757b4d531baa8dfb48c8009517d2d21cb5 100644 (file)
--- a/drivers/usb/serial/ssu100.c
+++ b/drivers/usb/serial/ssu100.c
@@ -61,7 +61,6 @@ struct ssu100_port_private {
        spinlock_t status_lock;
        u8 shadowLSR;
        u8 shadowMSR;
-       wait_queue_head_t delta_msr_wait; /* Used for TIOCMIWAIT */
        struct async_icount icount;
 };
 
@@ -355,8 +354,9 @@ static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
        spin_unlock_irqrestore(&priv->status_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)));
@@ -364,6 +364,9 @@ 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->status_lock, flags);
                cur = priv->icount;
                spin_unlock_irqrestore(&priv->status_lock, flags);
@@ -445,7 +448,6 @@ static int ssu100_port_probe(struct usb_serial_port *port)
                return -ENOMEM;
 
        spin_lock_init(&priv->status_lock);
-       init_waitqueue_head(&priv->delta_msr_wait);
 
        usb_set_serial_port_data(port, priv);
 
@@ -537,7 +539,7 @@ static void ssu100_update_msr(struct usb_serial_port *port, u8 msr)
                        priv->icount.dcd++;
                if (msr & UART_MSR_TERI)
                        priv->icount.rng++;
-               wake_up_interruptible(&priv->delta_msr_wait);
+               wake_up_interruptible(&port->delta_msr_wait);
        }
 }