static bool net_tx_pkt_parse_headers(struct NetTxPkt *pkt)
{
    struct iovec *l2_hdr, *l3_hdr;
    size_t bytes_read;
    size_t full_ip6hdr_len;
    uint16_t l3_proto;

    assert(pkt);

    l2_hdr = &pkt->vec[NET_TX_PKT_L2HDR_FRAG];
    l3_hdr = &pkt->vec[NET_TX_PKT_L3HDR_FRAG];

    bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags, 0, l2_hdr->iov_base,
                            ETH_MAX_L2_HDR_LEN);
    if (bytes_read < sizeof(struct eth_header)) {
        l2_hdr->iov_len = 0;
        return false;
    }

    l2_hdr->iov_len = sizeof(struct eth_header);
    switch (be16_to_cpu(PKT_GET_ETH_HDR(l2_hdr->iov_base)->h_proto)) {
    case ETH_P_VLAN:
        l2_hdr->iov_len += sizeof(struct vlan_header);
        break;
    case ETH_P_DVLAN:
        l2_hdr->iov_len += 2 * sizeof(struct vlan_header);
        break;
    }

    if (bytes_read < l2_hdr->iov_len) {
        l2_hdr->iov_len = 0;
        l3_hdr->iov_len = 0;
        pkt->packet_type = ETH_PKT_UCAST;
        return false;
    } else {
        l2_hdr->iov_len = ETH_MAX_L2_HDR_LEN;
        l2_hdr->iov_len = eth_get_l2_hdr_length(l2_hdr->iov_base);
        pkt->packet_type = get_eth_packet_type(l2_hdr->iov_base);
    }

    l3_proto = eth_get_l3_proto(l2_hdr, 1, l2_hdr->iov_len);

    switch (l3_proto) {
    case ETH_P_IP:
        bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags, l2_hdr->iov_len,
                                l3_hdr->iov_base, sizeof(struct ip_header));

        if (bytes_read < sizeof(struct ip_header)) {
            l3_hdr->iov_len = 0;
            return false;
        }

        l3_hdr->iov_len = IP_HDR_GET_LEN(l3_hdr->iov_base);

        if (l3_hdr->iov_len < sizeof(struct ip_header)) {
            l3_hdr->iov_len = 0;
            return false;
        }

        pkt->l4proto = ((struct ip_header *) l3_hdr->iov_base)->ip_p;

        if (IP_HDR_GET_LEN(l3_hdr->iov_base) != sizeof(struct ip_header)) {
            /* copy optional IPv4 header data if any*/
            bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags,
                                    l2_hdr->iov_len + sizeof(struct ip_header),
                                    l3_hdr->iov_base + sizeof(struct ip_header),
                                    l3_hdr->iov_len - sizeof(struct ip_header));
            if (bytes_read < l3_hdr->iov_len - sizeof(struct ip_header)) {
                l3_hdr->iov_len = 0;
                return false;
            }
        }

        break;

    case ETH_P_IPV6:
    {
        eth_ip6_hdr_info hdrinfo;

        if (!eth_parse_ipv6_hdr(pkt->raw, pkt->raw_frags, l2_hdr->iov_len,
                                &hdrinfo)) {
            l3_hdr->iov_len = 0;
            return false;
        }

        pkt->l4proto = hdrinfo.l4proto;
        full_ip6hdr_len = hdrinfo.full_hdr_len;

        if (full_ip6hdr_len > ETH_MAX_IP_DGRAM_LEN) {
            l3_hdr->iov_len = 0;
            return false;
        }

        bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags, l2_hdr->iov_len,
                                l3_hdr->iov_base, full_ip6hdr_len);

        if (bytes_read < full_ip6hdr_len) {
            l3_hdr->iov_len = 0;
            return false;
        } else {
            l3_hdr->iov_len = full_ip6hdr_len;
        }
        break;
    }
    default:
        l3_hdr->iov_len = 0;
        break;
    }

    net_tx_pkt_calculate_hdr_len(pkt);
    return true;
}

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.