USB: fix race in visor_write

this fixes a small race in visor_write.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/visor.c b/drivers/usb/serial/visor.c
index 2f59ff2..ffbe601 100644 (file)
--- a/drivers/usb/serial/visor.c
+++ b/drivers/usb/serial/visor.c
@@ -384,19 +384,21 @@ static int visor_write (struct usb_serial_port *port, const unsigned char *buf,
                dbg("%s - write limit hit\n", __FUNCTION__);
                return 0;
        }
+       priv->outstanding_urbs++;
        spin_unlock_irqrestore(&priv->lock, flags);
 
        buffer = kmalloc (count, GFP_ATOMIC);
        if (!buffer) {
                dev_err(&port->dev, "out of memory\n");
-               return -ENOMEM;
+               count = -ENOMEM;
+               goto error_no_buffer;
        }
 
        urb = usb_alloc_urb(0, GFP_ATOMIC);
        if (!urb) {
                dev_err(&port->dev, "no more free urbs\n");
-               kfree (buffer);
-               return -ENOMEM;
+               count = -ENOMEM;
+               goto error_no_urb;
        }
 
        memcpy (buffer, buf, count);
@@ -415,18 +417,26 @@ static int visor_write (struct usb_serial_port *port, const unsigned char *buf,
                dev_err(&port->dev, "%s - usb_submit_urb(write bulk) failed with status = %d\n",
                        __FUNCTION__, status);
                count = status;
-               kfree (buffer);
+               goto error;
        } else {
                spin_lock_irqsave(&priv->lock, flags);
-               ++priv->outstanding_urbs;
                priv->bytes_out += count;
                spin_unlock_irqrestore(&priv->lock, flags);
        }
 
        /* we are done with this urb, so let the host driver
         * really free it when it is finished with it */
-       usb_free_urb (urb);
+       usb_free_urb(urb);
 
+       return count;
+error:
+       usb_free_urb(urb);
+error_no_urb:
+       kfree(buffer);
+error_no_buffer:
+       spin_lock_irqsave(&priv->lock, flags);
+       --priv->outstanding_urbs;
+       spin_unlock_irqrestore(&priv->lock, flags);
        return count;
 }