int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
    int *num, uint64_t *host_offset, QCowL2Meta **m)
{
    BDRVQcowState *s = bs->opaque;
    uint64_t start, remaining;
    uint64_t cluster_offset;
    uint64_t cur_bytes;
    int ret;

    trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset, *num);

    assert((offset & ~BDRV_SECTOR_MASK) == 0);

again:
    start = offset;
    remaining = *num << BDRV_SECTOR_BITS;
    cluster_offset = 0;
    *host_offset = 0;
    cur_bytes = 0;
    *m = NULL;

    while (true) {

        if (!*host_offset) {
            *host_offset = start_of_cluster(s, cluster_offset);
        }

        assert(remaining >= cur_bytes);

        start           += cur_bytes;
        remaining       -= cur_bytes;
        cluster_offset  += cur_bytes;

        if (remaining == 0) {
            break;
        }

        cur_bytes = remaining;

        /*
         * Now start gathering as many contiguous clusters as possible:
         *
         * 1. Check for overlaps with in-flight allocations
         *
         *      a) Overlap not in the first cluster -> shorten this request and
         *         let the caller handle the rest in its next loop iteration.
         *
         *      b) Real overlaps of two requests. Yield and restart the search
         *         for contiguous clusters (the situation could have changed
         *         while we were sleeping)
         *
         *      c) TODO: Request starts in the same cluster as the in-flight
         *         allocation ends. Shorten the COW of the in-fight allocation,
         *         set cluster_offset to write to the same cluster and set up
         *         the right synchronisation between the in-flight request and
         *         the new one.
         */
        ret = handle_dependencies(bs, start, &cur_bytes, m);
        if (ret == -EAGAIN) {
            /* Currently handle_dependencies() doesn't yield if we already had
             * an allocation. If it did, we would have to clean up the L2Meta
             * structs before starting over. */
            assert(*m == NULL);
            goto again;
        } else if (ret < 0) {
            return ret;
        } else if (cur_bytes == 0) {
            break;
        } else {
            /* handle_dependencies() may have decreased cur_bytes (shortened
             * the allocations below) so that the next dependency is processed
             * correctly during the next loop iteration. */
        }

        /*
         * 2. Count contiguous COPIED clusters.
         */
        ret = handle_copied(bs, start, &cluster_offset, &cur_bytes, m);
        if (ret < 0) {
            return ret;
        } else if (ret) {
            continue;
        } else if (cur_bytes == 0) {
            break;
        }

        /*
         * 3. If the request still hasn't completed, allocate new clusters,
         *    considering any cluster_offset of steps 1c or 2.
         */
        ret = handle_alloc(bs, start, &cluster_offset, &cur_bytes, m);
        if (ret < 0) {
            return ret;
        } else if (ret) {
            continue;
        } else {
            assert(cur_bytes == 0);
            break;
        }
    }

    *num -= remaining >> BDRV_SECTOR_BITS;
    assert(*num > 0);
    assert(*host_offset != 0);

    return 0;
}

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.