uint32_t virtio_config_modern_readb(VirtIODevice *vdev, uint32_t addr)
{
    VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
    uint8_t val;

    if (addr + sizeof(val) > vdev->config_len) {
        return (uint32_t)-1;
    }

    k->get_config(vdev, vdev->config);

    val = ldub_p(vdev->config + addr);
    return val;
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.