static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,
                                 struct iovec *iov, unsigned int iov_cnt)
{
    struct virtio_net_ctrl_mac mac_data;
    size_t s;
    NetClientState *nc = qemu_get_queue(n->nic);

    if (cmd == VIRTIO_NET_CTRL_MAC_ADDR_SET) {
        if (iov_size(iov, iov_cnt) != sizeof(n->mac)) {
            return VIRTIO_NET_ERR;
        }
        s = iov_to_buf(iov, iov_cnt, 0, &n->mac, sizeof(n->mac));
        assert(s == sizeof(n->mac));
        qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac);
        rxfilter_notify(nc);

        return VIRTIO_NET_OK;
    }

    if (cmd != VIRTIO_NET_CTRL_MAC_TABLE_SET) {
        return VIRTIO_NET_ERR;
    }

    int in_use = 0;
    int first_multi = 0;
    uint8_t uni_overflow = 0;
    uint8_t multi_overflow = 0;
    uint8_t *macs = g_malloc0(MAC_TABLE_ENTRIES * ETH_ALEN);

    s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
                   sizeof(mac_data.entries));
    mac_data.entries = ldl_p(&mac_data.entries);
    if (s != sizeof(mac_data.entries)) {
        goto error;
    }
    iov_discard_front(&iov, &iov_cnt, s);

    if (mac_data.entries * ETH_ALEN > iov_size(iov, iov_cnt)) {
        goto error;
    }

    if (mac_data.entries <= MAC_TABLE_ENTRIES) {
        s = iov_to_buf(iov, iov_cnt, 0, macs,
                       mac_data.entries * ETH_ALEN);
        if (s != mac_data.entries * ETH_ALEN) {
            goto error;
        }
        in_use += mac_data.entries;
    } else {
        uni_overflow = 1;
    }

    iov_discard_front(&iov, &iov_cnt, mac_data.entries * ETH_ALEN);

    first_multi = in_use;

    s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
                   sizeof(mac_data.entries));
    mac_data.entries = ldl_p(&mac_data.entries);
    if (s != sizeof(mac_data.entries)) {
        goto error;
    }

    iov_discard_front(&iov, &iov_cnt, s);

    if (mac_data.entries * ETH_ALEN != iov_size(iov, iov_cnt)) {
        goto error;
    }

    if (mac_data.entries <= MAC_TABLE_ENTRIES - in_use) {
        s = iov_to_buf(iov, iov_cnt, 0, &macs[in_use * ETH_ALEN],
                       mac_data.entries * ETH_ALEN);
        if (s != mac_data.entries * ETH_ALEN) {
            goto error;
        }
        in_use += mac_data.entries;
    } else {
        multi_overflow = 1;
    }

    n->mac_table.in_use = in_use;
    n->mac_table.first_multi = first_multi;
    n->mac_table.uni_overflow = uni_overflow;
    n->mac_table.multi_overflow = multi_overflow;
    memcpy(n->mac_table.macs, macs, MAC_TABLE_ENTRIES * ETH_ALEN);
    g_free(macs);
    rxfilter_notify(nc);

    return VIRTIO_NET_OK;

error:
    g_free(macs);
    return VIRTIO_NET_ERR;
}

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.