static uint64_t ne2000_read(void *opaque, hwaddr addr,
                            unsigned size)
{
    NE2000State *s = opaque;

    if (addr < 0x10 && size == 1) {
        return ne2000_ioport_read(s, addr);
    } else if (addr == 0x10) {
        if (size <= 2) {
            return ne2000_asic_ioport_read(s, addr);
        } else {
            return ne2000_asic_ioport_readl(s, addr);
        }
    } else if (addr == 0x1f && size == 1) {
        return ne2000_reset_ioport_read(s, addr);
    }
    return ((uint64_t)1 << (size * 8)) - 1;
}

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.