USB: fix race in ftdio_write

this has the same race as the visor driver. The counter must be incremented
under the lock it is checked under.

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

1 files changed, 16 insertions, 6 deletions

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 8ff9d54b21e6..8fb8e2f64545 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1433,6 +1433,7 @@ static int ftdi_write (struct usb_serial_port *port,
                 dbg("%s - write limit hit\n", __FUNCTION__);
                 return 0;
         }
+        priv->tx_outstanding_urbs++;
         spin_unlock_irqrestore(&priv->tx_lock, flags);
 
         data_offset = priv->write_offset;
@@ -1450,14 +1451,15 @@ static int ftdi_write (struct usb_serial_port *port,
         buffer = kmalloc (transfer_size, GFP_ATOMIC);
         if (!buffer) {
                 err("%s ran out of kernel memory for urb ...", __FUNCTION__);
-                return -ENOMEM;
+                count = -ENOMEM;
+                goto error_no_buffer;
         }
 
         urb = usb_alloc_urb(0, GFP_ATOMIC);
         if (!urb) {
                 err("%s - no more free urbs", __FUNCTION__);
-                kfree (buffer);
-                return -ENOMEM;
+                count = -ENOMEM;
+                goto error_no_urb;
         }
 
         /* Copy data */
@@ -1499,10 +1501,9 @@ static int ftdi_write (struct usb_serial_port *port,
         if (status) {
                 err("%s - failed submitting write urb, error %d", __FUNCTION__, status);
                 count = status;
-                kfree (buffer);
+                goto error;
         } else {
                 spin_lock_irqsave(&priv->tx_lock, flags);
-                ++priv->tx_outstanding_urbs;
                 priv->tx_outstanding_bytes += count;
                 priv->tx_bytes += count;
                 spin_unlock_irqrestore(&priv->tx_lock, flags);
@@ -1510,10 +1511,19 @@ static int ftdi_write (struct usb_serial_port *port,
 
         /* 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);
 
         dbg("%s write returning: %d", __FUNCTION__, count);
         return count;
+error:
+        usb_free_urb(urb);
+error_no_urb:
+        kfree (buffer);
+error_no_buffer:
+        spin_lock_irqsave(&priv->tx_lock, flags);
+        priv->tx_outstanding_urbs--;
+        spin_unlock_irqrestore(&priv->tx_lock, flags);
+        return count;
 } /* ftdi_write */