int qcow2_read_snapshots(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;
    QCowSnapshotHeader h;
    QCowSnapshotExtraData extra;
    QCowSnapshot *sn;
    int i, id_str_size, name_size;
    int64_t offset;
    uint32_t extra_data_size;
    int ret;

    if (!s->nb_snapshots) {
        s->snapshots = NULL;
        s->snapshots_size = 0;
        return 0;
    }

    offset = s->snapshots_offset;
    s->snapshots = g_malloc0(s->nb_snapshots * sizeof(QCowSnapshot));

    for(i = 0; i < s->nb_snapshots; i++) {
        /* Read statically sized part of the snapshot header */
        offset = align_offset(offset, 8);
        ret = bdrv_pread(bs->file, offset, &h, sizeof(h));
        if (ret < 0) {
            goto fail;
        }

        offset += sizeof(h);
        sn = s->snapshots + i;
        sn->l1_table_offset = be64_to_cpu(h.l1_table_offset);
        sn->l1_size = be32_to_cpu(h.l1_size);
        sn->vm_state_size = be32_to_cpu(h.vm_state_size);
        sn->date_sec = be32_to_cpu(h.date_sec);
        sn->date_nsec = be32_to_cpu(h.date_nsec);
        sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec);
        extra_data_size = be32_to_cpu(h.extra_data_size);

        id_str_size = be16_to_cpu(h.id_str_size);
        name_size = be16_to_cpu(h.name_size);

        /* Read extra data */
        ret = bdrv_pread(bs->file, offset, &extra,
                         MIN(sizeof(extra), extra_data_size));
        if (ret < 0) {
            goto fail;
        }
        offset += extra_data_size;

        if (extra_data_size >= 8) {
            sn->vm_state_size = be64_to_cpu(extra.vm_state_size_large);
        }

        if (extra_data_size >= 16) {
            sn->disk_size = be64_to_cpu(extra.disk_size);
        } else {
            sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
        }

        /* Read snapshot ID */
        sn->id_str = g_malloc(id_str_size + 1);
        ret = bdrv_pread(bs->file, offset, sn->id_str, id_str_size);
        if (ret < 0) {
            goto fail;
        }
        offset += id_str_size;
        sn->id_str[id_str_size] = '\0';

        /* Read snapshot name */
        sn->name = g_malloc(name_size + 1);
        ret = bdrv_pread(bs->file, offset, sn->name, name_size);
        if (ret < 0) {
            goto fail;
        }
        offset += name_size;
        sn->name[name_size] = '\0';
    }

    s->snapshots_size = offset - s->snapshots_offset;
    return 0;

fail:
    qcow2_free_snapshots(bs);
    return ret;
}

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.