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

commit 43a66b4c417ad15f6d2f632ce67ad195bdf999e8 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/ssu100.c b/drivers/usb/serial/ssu100.c
index d938396171e87f22dd4f1f685dc3d33cccf751a9..44d59497ffe26c9b3e37d5fbcecbfd574b2f5227 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);
        }
 }