hso: Fix crashes on close.

Moved serial_open_count in hso_serial_open to
prevent crashes owing to the serial structure being made NULL
when hso_serial_close is called even though hso_serial_open
returned -ENODEV, Alan Cox pointed out this happens,
also put in sanity check in hso_serial_close
to check for a valid serial structure which should prevent
the most reproducable crash in the driver when the hso device
is disconnected while in use.

Signed-off-by: Denis Joseph Barrow <D.Barow@option.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 2 deletions

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index cee1d2a280bd..d5857321979b 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -1235,6 +1235,11 @@ static int hso_serial_open(struct tty_struct *tty, struct file *filp)
         }
 
         mutex_lock(&serial->parent->mutex);
+        /* check for port already opened, if not set the termios */
+        /* The serial->open count needs to be here as hso_serial_close
+         *  will be called even if hso_serial_open returns -ENODEV.
+         */
+        serial->open_count++;
         result = usb_autopm_get_interface(serial->parent->interface);
         if (result < 0)
                 goto err_out;
@@ -1246,8 +1251,6 @@ static int hso_serial_open(struct tty_struct *tty, struct file *filp)
         tty->driver_data = serial;
         serial->tty = tty;
 
-        /* check for port already opened, if not set the termios */
-        serial->open_count++;
         if (serial->open_count == 1) {
                 tty->low_latency = 1;
                 serial->rx_state = RX_IDLE;
@@ -1285,6 +1288,10 @@ static void hso_serial_close(struct tty_struct *tty, struct file *filp)
         u8 usb_gone;
 
         D1("Closing serial port");
+        if (serial == NULL || serial->magic != HSO_SERIAL_MAGIC) {
+                D1("invalid serial structure bailing out.\n");
+                return;
+        }
 
         mutex_lock(&serial->parent->mutex);
         usb_gone = serial->parent->usb_gone;