juniper_frelay_print(netdissect_options *ndo,
                     const struct pcap_pkthdr *h, register const u_char *p)
{
        struct juniper_l2info_t l2info;

        l2info.pictype = DLT_JUNIPER_FRELAY;
        if (juniper_parse_header(ndo, p, h, &l2info) == 0)
            return l2info.header_len;

        p+=l2info.header_len;
        /* this DLT contains nothing but raw frame-relay frames */
        fr_print(ndo, p, l2info.length);
        return l2info.header_len;
}

The product reads data past the end, or before the beginning, of the intended buffer.