void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,
                             int nb_clusters, enum qcow2_discard_type type)
{
    BDRVQcowState *s = bs->opaque;

    switch (qcow2_get_cluster_type(l2_entry)) {
    case QCOW2_CLUSTER_COMPRESSED:
        {
            int nb_csectors;
            nb_csectors = ((l2_entry >> s->csize_shift) &
                           s->csize_mask) + 1;
            qcow2_free_clusters(bs,
                (l2_entry & s->cluster_offset_mask) & ~511,
                nb_csectors * 512, type);
        }
        break;
    case QCOW2_CLUSTER_NORMAL:
    case QCOW2_CLUSTER_ZERO:
        if (l2_entry & L2E_OFFSET_MASK) {
            qcow2_free_clusters(bs, l2_entry & L2E_OFFSET_MASK,
                                nb_clusters << s->cluster_bits, type);
        }
        break;
    case QCOW2_CLUSTER_UNALLOCATED:
        break;
    default:
        abort();
    }
}

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.