Hack strcmp

i need to hack a strcmp to go in the if and pass a command in the system. The program is a server when i lunch the server i lunch a client normaly with a command using "handlerBuyIngredient" i can pass a line like ";reboot" with it and being use by the system under the if but i don't know how to hack the if with the strcmp cause i cn't overflow the strcmp.

normaly with the system i can send some comand to other person who are conected with the same port to the server.

static int
handlerBuyIngredient(void *packetPtr, size_t packetSize)
{
  int                   i;
  char                  *ingredientName;
  int                   amount;
  char                  log[128];
  char                  *password = NULL;

  password = getStr(&packetPtr, &packetSize);
  if (checkPassword(password) == ADMIN) {
    ingredientName = getStr(&packetPtr, &packetSize);
    amount = getNumber(&packetPtr, &packetSize);for (i = 0; stock[i].name != NULL; ++i) {
      if (!strcmp(ingredientName, stock[i].name)) {
        puts("PASS");
        money -= 2 * amount;
    stock[i].quantity += amount;
        sendLogMessage(INGREDIENT_BOUGHT);
        sprintf(log, "echo \"%s was bought\" >> log", ingredientName);
        free(ingredientName);
        system(log);
        return amount;
      }
    }
    sendLogMessage(UNKNOWN_INGREDIENT);
  }
  return -1;
}

Your brain had obviously had a tremendous overflow