Date: Thu, 01 Jul 1999 10:02:36 -0500 From: venkat venkatsubra <venkats@austin.ibm.com> To: Witman Peng <witman@iname.com> Cc: freebsd-net@FreeBSD.ORG, freebsd-bugs@FreeBSD.ORG Subject: Re: IP reassemble fails if it contains more that 20 bytes options? Message-ID: <377B830C.EE4A82E7@austin.ibm.com> References: <000101bec374$30e06eb0$010000c8@heart.witman.com>
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Witman, Isn't this taken care of early in ipintr ? -------------------------- if (hlen > m->m_len) { if ((m = m_pullup(m, hlen)) == 0) { ipstat.ips_badhlen++; goto next; } ip = mtod(m, struct ip *); } --------------------------- Venkat Witman Peng wrote: > Hi, All > > I am developing an application based on 4.4BSD-Lite source code. When I port > the code in file netinet/ip_input.c, I found a problem. But I have no chance > to install FreeBSD and test it, so I am not sure whether it'a bug or not. > The following are the code to reassemble the IP fragments from ip_input.c: > > >From routine ipintr: > if (ip->ip_off &~ IP_DF) { > if (m->m_flags & M_EXT) { /* XXX */ > if ((m = m_pullup(m, sizeof (struct ip))) == 0) { > ipstat.ips_toosmall++; > goto next; > } > ip = mtod(m, struct ip *); > } > > >From routine ip_reass: > int hlen = ip->ip_hl << 2; > int i, next; > > m->m_data += hlen; > m->m_len -= hlen; > > Suppose a fragment with more that 208 bytes and 40 bytes IP option, it will > be stored in the cluster but not mbuf. In routine ipintr, function pullup > just pullup sizeof(struct ip) (maybe 40 bytes for tcp header) bytes into a > new mbuf. However, the IP header is 60 (20 + 40) bytes, so the complete IP > header cannot be stored in this mbuf. Then in routine ip_reass, after run > the above code, m->m_data will pointer to an incorrect address. > > Dose it seems right? Any inputs would be apprecaited. > > BR, > Witman Peng > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-net" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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