local void log_init(void)
{
    if (log_tail == NULL) {
        mem_track.num = 0;
        mem_track.size = 0;
        mem_track.max = 0;
#ifndef NOTHREAD
        mem_track.lock = new_lock(0);
        yarn_mem(yarn_malloc, yarn_free);
        log_lock = new_lock(0);
#endif
        log_head = NULL;
        log_tail = &log_head;
    }
}

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.