ALLEGRO_FILE *memfile = al_open_memfile(buffer, file_size, "rb");

    std::string fn = file_name;
    fn.append(file_type);

    f = al_load_ttf_font_f(memfile, fn.c_str(), size, flags);

    //al_fclose(memfile);

Note that I have commented out al_fclose(memfile);
This way it doesn't crash. However, if I close the memfile, it will crash as soon as the game has to draw some text using the loaded font.

http://www.allegro.cc/manual/5/al_load_ttf_font_f
says:
Note: The file handle is owned by the returned ALLEGRO_FONT object and must not be freed by the caller, as FreeType expects to be able to read from it at a later time.

To my understanding, the note says that I am not supposed to free buffer.

So do I get it right - I must not al_fclose the memfile and I must not al_free the buffer?

Thanks. Do I have to al_fclose the memfile too after having freed the memory?