void qcow2_free_clusters(BlockDriverState *bs,
                          int64_t offset, int64_t size,
                          enum qcow2_discard_type type)
{
    int ret;

    BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_FREE);
    ret = update_refcount(bs, offset, size, -1, type);
    if (ret < 0) {
        fprintf(stderr, "qcow2_free_clusters failed: %s\n", strerror(-ret));
        /* TODO Remember the clusters to free them later and avoid leaking */
    }
}

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.