int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
    int nb_sectors, enum qcow2_discard_type type)
{
    BDRVQcowState *s = bs->opaque;
    uint64_t end_offset;
    unsigned int nb_clusters;
    int ret;

    end_offset = offset + (nb_sectors << BDRV_SECTOR_BITS);

    /* Round start up and end down */
    offset = align_offset(offset, s->cluster_size);
    end_offset = start_of_cluster(s, end_offset);

    if (offset > end_offset) {
        return 0;
    }

    nb_clusters = size_to_clusters(s, end_offset - offset);

    s->cache_discards = true;

    /* Each L2 table is handled by its own loop iteration */
    while (nb_clusters > 0) {
        ret = discard_single_l2(bs, offset, nb_clusters, type);
        if (ret < 0) {
            goto fail;
        }

        nb_clusters -= ret;
        offset += (ret * s->cluster_size);
    }

    ret = 0;
fail:
    s->cache_discards = false;
    qcow2_process_discards(bs, ret);

    return ret;
}

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.