static inline signed int ReadPropertySignedLong(const EndianType endian,
  const unsigned char *buffer)
{
  union
  {
    unsigned int
      unsigned_value;

    signed int
      signed_value;
  } quantum;

  unsigned int
    value;

  if (endian == LSBEndian)
    {
      value=(unsigned int) buffer[3] << 24;
      value|=(unsigned int) buffer[2] << 16;
      value|=(unsigned int) buffer[1] << 8;
      value|=(unsigned int) buffer[0];
      quantum.unsigned_value=value & 0xffffffff;
      return(quantum.signed_value);
    }
  value=(unsigned int) buffer[0] << 24;
  value|=(unsigned int) buffer[1] << 16;
  value|=(unsigned int) buffer[2] << 8;
  value|=(unsigned int) buffer[3];
  quantum.unsigned_value=value & 0xffffffff;
  return(quantum.signed_value);
}

The product reads data past the end, or before the beginning, of the intended buffer.