enum AVPixelFormat avpriv_find_pix_fmt(const PixelFormatTag *tags,
                                       unsigned int fourcc)
{
    while (tags->pix_fmt >= 0) {
        if (tags->fourcc == fourcc)
            return tags->pix_fmt;
        tags++;
    }
    return AV_PIX_FMT_NONE;
}

The product writes data past the end, or before the beginning, of the intended buffer.