static int zero_single_l2(BlockDriverState *bs, uint64_t offset,
    unsigned int nb_clusters)
{
    BDRVQcowState *s = bs->opaque;
    uint64_t *l2_table;
    int l2_index;
    int ret;
    int i;

    ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
    if (ret < 0) {
        return ret;
    }

    /* Limit nb_clusters to one L2 table */
    nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);

    for (i = 0; i < nb_clusters; i++) {
        uint64_t old_offset;

        old_offset = be64_to_cpu(l2_table[l2_index + i]);

        /* Update L2 entries */
        qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
        if (old_offset & QCOW_OFLAG_COMPRESSED) {
            l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
            qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
        } else {
            l2_table[l2_index + i] |= cpu_to_be64(QCOW_OFLAG_ZERO);
        }
    }

    ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
    if (ret < 0) {
        return ret;
    }

    return nb_clusters;
}

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.