static int qcow2_truncate(BlockDriverState *bs, int64_t offset)
{
    BDRVQcowState *s = bs->opaque;
    int64_t new_l1_size;
    int ret;

    if (offset & 511) {
        error_report("The new size must be a multiple of 512");
        return -EINVAL;
    }

    /* cannot proceed if image has snapshots */
    if (s->nb_snapshots) {
        error_report("Can't resize an image which has snapshots");
        return -ENOTSUP;
    }

    /* shrinking is currently not supported */
    if (offset < bs->total_sectors * 512) {
        error_report("qcow2 doesn't support shrinking images yet");
        return -ENOTSUP;
    }

    new_l1_size = size_to_l1(s, offset);
    ret = qcow2_grow_l1_table(bs, new_l1_size, true);
    if (ret < 0) {
        return ret;
    }

    /* write updated header.size */
    offset = cpu_to_be64(offset);
    ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, size),
                           &offset, sizeof(uint64_t));
    if (ret < 0) {
        return ret;
    }

    s->l1_vm_state_index = new_l1_size;
    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.