race condition

[jingsong-liu]

 int new_fd = accept(server_sock, (struct sockaddr*)&client_addr, &client_addr_len);
...
 cargs.fd = new_fd;
 if(0 != pthread_create(&pid, NULL, cli_conn, (void *)&cargs)) {
...

void *
cli_conn(void* arg)
{
    int sock = ((struct cli_args*)arg)->fd;
...

There is a race condition between accept a connection and thread routine's assigning new connection fd to sock, if next accept comes before current connection thread's sock assignment, int sock = ((struct cli_args*)arg)->fd, then two connection thread will refer to same socket file description, its dangerous.