static ssize_t eth_rx(NetClientState *nc, const uint8_t *buf, size_t size)
{
    struct xlx_ethlite *s = qemu_get_nic_opaque(nc);
    unsigned int rxbase = s->rxbuf * (0x800 / 4);

    /* DA filter.  */
    if (!(buf[0] & 0x80) && memcmp(&s->conf.macaddr.a[0], buf, 6))
        return size;

    if (s->regs[rxbase + R_RX_CTRL0] & CTRL_S) {
        D(qemu_log("ethlite lost packet %x\n", s->regs[R_RX_CTRL0]));
        return -1;
     }
 
     D(qemu_log("%s %zd rxbase=%x\n", __func__, size, rxbase));
     memcpy(&s->regs[rxbase + R_RX_BUF0], buf, size);
 
     s->regs[rxbase + R_RX_CTRL0] |= CTRL_S;
    /* If c_rx_pingpong was set flip buffers.  */
    s->rxbuf ^= s->c_rx_pingpong;
    return size;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.