[PATCH 3.18 19/39] USB: serial: digi_acceleport: fix incomplete rx sanity check

[Greg Kroah-Hartman]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <jo...@kernel.org>

commit 1b0aed2b1600f6e5c7b9acfbd610a4e351ef5232 upstream.

Make sure the received data has the required headers before parsing it.

Also drop the redundant urb-status check, which has already been handled
by the caller.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Signed-off-by: Johan Hovold <jo...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/usb/serial/digi_acceleport.c |   38 +++++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 15 deletions(-)

--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -1399,25 +1399,30 @@ static int digi_read_inb_callback(struct
 {
        struct usb_serial_port *port = urb->context;
        struct digi_port *priv = usb_get_serial_port_data(port);
-       int opcode = ((unsigned char *)urb->transfer_buffer)[0];
-       int len = ((unsigned char *)urb->transfer_buffer)[1];
-       int port_status = ((unsigned char *)urb->transfer_buffer)[2];
-       unsigned char *data = ((unsigned char *)urb->transfer_buffer) + 3;
+       unsigned char *buf = urb->transfer_buffer;
+       int opcode;
+       int len;
+       int port_status;
+       unsigned char *data;
        int flag, throttled;
-       int status = urb->status;
-
-       /* do not process callbacks on closed ports */
-       /* but do continue the read chain */
-       if (urb->status == -ENOENT)
-               return 0;
 
        /* short/multiple packet check */
+       if (urb->actual_length < 2) {
+               dev_warn(&port->dev, "short packet received\n");
+               return -1;
+       }
+
+       opcode = buf[0];
+       len = buf[1];
+
        if (urb->actual_length != len + 2) {
-               dev_err(&port->dev, "%s: INCOMPLETE OR MULTIPLE PACKET, "
-                       "status=%d, port=%d, opcode=%d, len=%d, "
-                       "actual_length=%d, status=%d\n", __func__, status,
-                       priv->dp_port_num, opcode, len, urb->actual_length,
-                       port_status);
+               dev_err(&port->dev, "malformed packet received: port=%d, 
opcode=%d, len=%d, actual_length=%u\n",
+                       priv->dp_port_num, opcode, len, urb->actual_length);
+               return -1;
+       }
+
+       if (opcode == DIGI_CMD_RECEIVE_DATA && len < 1) {
+               dev_err(&port->dev, "malformed data packet received\n");
                return -1;
        }
 
@@ -1431,6 +1436,9 @@ static int digi_read_inb_callback(struct
 
        /* receive data */
        if (opcode == DIGI_CMD_RECEIVE_DATA) {
+               port_status = buf[2];
+               data = &buf[3];
+
                /* get flag from port_status */
                flag = 0;