I am doing a application witch uses sockets so I am holding in an array the sockets handles.I have the following code:

while(0 == 0){


                int * tx = (int*)(malloc((nr_con + 2) * sizeof(int)));
                if (conexiuni != NULL)
                {
                syslog(LOG_NOTICE,"Ajung la eliberare %d",nr_con);
                memcpy(&tx[0],&conexiuni[0],(sizeof(int) * (nr_con)));
                syslog(LOG_NOTICE,"Ajung la eliberare %d",nr_con);
                free(conexiuni);
                }
                conexiuni = tx;

                syslog(LOG_NOTICE,"Ajung la mama %d",nr_con);
                            //The line bellow causes a segfault at second connection
                if ((conexiuni[nr_con] = accept(hsock,(sockaddr*)(&sadr),&addr_size)) != -1)
                                {
                                    nr_con++;
                                    syslog(LOG_NOTICE,"Primesc de la %s",inet_ntoa(sadr.sin_addr));
                                    syslog(LOG_NOTICE,"kkt %d",conexiuni[nr_con - 1]);
                                    int * sz = (int*)malloc(sizeof(int));
                                    *sz = conexiuni[nr_con - 1];
                                    syslog(LOG_NOTICE,"after %d",*sz);
                                    pthread_create(&tidi,0,&ConexiuniHandler, sz);
                                }



            }

When I connect the second time when I assign the array the program crashes. What am I doing wrong? I tried the same code on Windows and it works well but on Linux it crashes.