关于引起OpenSSL的heartbleed的问题代码

Question

 void process_heartbeat(unsigned char *hbMessage){
     unsigned short hbtype;
     unsigned int payload;
     unsigned char* contents;
     hbtype = hbMessage[0];
     payload = (((unsigned int)(hbMessage[1])<<8)
                                        |(((unsigned int)(hbMessage[2])));
    hbMessage += 3;
    contents = hbMessage;
    if(hbtype == TLS1_HB_REQUEST){
            unsigned char* response;
            response=(unsigned char *)malloc(1+2+payload+padding);
            ...
            memcpy(response,pl,payload);
            ...
            }
            ...
     }

上面这段代码会引发heartbleed问题 具体是什么情况