USB: serial: io_edgeport: fix use after free in debug printk

commit 37bb5628379295c1254c113a407cab03a0f4d0b4 upstream.

The "dev_dbg(&urb->dev->dev, ..." which happens after usb_free_urb(urb)
is a use after free of the "urb" pointer.  Store the "dev" pointer at the
start of the function to avoid this issue.

Fixes: 984f68683298 ("USB: serial: io_edgeport.c: remove dbg() usage")
Cc: stable@vger.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
index 4b48ef4adbeb6f6a4c05aa249625563279ce875d..618e2b16e2043522f66d5ae10c01be153aeb574b 100644 (file)
--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -846,11 +846,12 @@ static void edge_bulk_out_data_callback(struct urb *urb)
 static void edge_bulk_out_cmd_callback(struct urb *urb)
 {
        struct edgeport_port *edge_port = urb->context;
+       struct device *dev = &urb->dev->dev;
        int status = urb->status;
 
        atomic_dec(&CmdUrbs);
-       dev_dbg(&urb->dev->dev, "%s - FREE URB %p (outstanding %d)\n",
-               __func__, urb, atomic_read(&CmdUrbs));
+       dev_dbg(dev, "%s - FREE URB %p (outstanding %d)\n", __func__, urb,
+               atomic_read(&CmdUrbs));
 
 
        /* clean up the transfer buffer */
@@ -860,8 +861,7 @@ static void edge_bulk_out_cmd_callback(struct urb *urb)
        usb_free_urb(urb);
 
        if (status) {
-               dev_dbg(&urb->dev->dev,
-                       "%s - nonzero write bulk status received: %d\n",
+               dev_dbg(dev, "%s - nonzero write bulk status received: %d\n",
                        __func__, status);
                return;
        }