In this chall, the flag is protected by a check that is never false:

  volatile bool check = true;
  uint32_t cnt = 0;
  int i = 0;
  int j;

  while (true) {
    cnt = 0;
    for (i = 0; i < 1000; i++) {
      for (j = 0; j < 1000; j++) {
        cnt++;
        if (!check) {
          // Flag gets printed
        }
      }
    }
    uart_printf("%u %u %u\r\n", i, j, cnt);
  }

Hint 1

Hint 2

Hint 3

Solution