[ECOS] Serial Driver imrpovement

["Graves, Daniel (GE Healthcare)" <Daniel.Graves@ge.com>]

Hello,

Note that this might have been fixed already but just in case:

I found that the following code in Serial.c will cause a buffer overflow if there is garbage data on the wire before a thread has started reading from the serial port:

------------------------------------------------
     static rcv_req_reply_t
     serial_data_rcv_req(serial_channel *chan, int avail, 
                    int* space_avail, unsigned char** space)
    {   
        cbuf_t *cbuf = &chan->in_cbuf;
        int gap;

        #ifdef CYGOPT_IO_SERIAL_FLOW_CONTROL_SOFTWARE
       // When there is software flow-control, force the serial device
      // driver to use the single-char xmt/rcv functions, since these
      // have to make policy decision based on the data. Rcv function
     // may also have to transmit data to throttle the xmitter.
       If (chan->config.flags & (CYGNUM_SERIAL_FLOW_XONXOFF_TX|CYGNUM_SERIAL_FLOW_XONXOFF_RX))
            return CYG_RCV_DISABLED;
        #endif

        CYG_ASSERT(false == cbuf->block_mode_xfer_running,
                   "Attempting new block transfer while another is running");
       // Check for space
       gap = cbuf->nb;
       if (gap == cbuf->len)
           return CYG_RCV_FULL;

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

The line gap == cbuf->len will not always evaluate to true if garbage data is received.  This will cause the put variable to shoot way past len.

Thanks,

Daniel P Graves

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