static int mov_read_stsz(MOVContext *c, AVIOContext *pb, MOVAtom atom)
{
    AVStream *st;
    MOVStreamContext *sc;
    unsigned int i, entries, sample_size, field_size, num_bytes;
    GetBitContext gb;
    unsigned char* buf;

    if (c->fc->nb_streams < 1)
        return 0;
    st = c->fc->streams[c->fc->nb_streams-1];
    sc = st->priv_data;

    avio_r8(pb); /* version */
    avio_rb24(pb); /* flags */

    if (atom.type == MKTAG('s','t','s','z')) {
        sample_size = avio_rb32(pb);
        if (!sc->sample_size) /* do not overwrite value computed in stsd */
            sc->sample_size = sample_size;
        sc->alt_sample_size = sample_size;
        field_size = 32;
    } else {
        sample_size = 0;
        avio_rb24(pb); /* reserved */
        field_size = avio_r8(pb);
    }
    entries = avio_rb32(pb);

    av_dlog(c->fc, "sample_size = %d sample_count = %d\n", sc->sample_size, entries);

    sc->sample_count = entries;
    if (sample_size)
        return 0;

    if (field_size != 4 && field_size != 8 && field_size != 16 && field_size != 32) {
        av_log(c->fc, AV_LOG_ERROR, "Invalid sample field size %d\n", field_size);
        return AVERROR_INVALIDDATA;
    }

    if (!entries)
        return 0;
    if (entries >= UINT_MAX / sizeof(int) || entries >= (UINT_MAX - 4) / field_size)
        return AVERROR_INVALIDDATA;
    sc->sample_sizes = av_malloc(entries * sizeof(int));
    if (!sc->sample_sizes)
        return AVERROR(ENOMEM);

    num_bytes = (entries*field_size+4)>>3;

    buf = av_malloc(num_bytes+FF_INPUT_BUFFER_PADDING_SIZE);
    if (!buf) {
        av_freep(&sc->sample_sizes);
        return AVERROR(ENOMEM);
    }

    if (avio_read(pb, buf, num_bytes) < num_bytes) {
        av_freep(&sc->sample_sizes);
        av_free(buf);
        return AVERROR_INVALIDDATA;
    }

    init_get_bits(&gb, buf, 8*num_bytes);

    for (i = 0; i < entries; i++) {
        sc->sample_sizes[i] = get_bits_long(&gb, field_size);
        sc->data_size += sc->sample_sizes[i];
    }

    av_free(buf);
    return 0;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.