Date: Tue, 1 Feb 2011 03:02:06 +0000 (UTC) From: "Bjoern A. Zeeb" <bz@FreeBSD.org> To: Lawrence Stewart <lstewart@freebsd.org> Cc: Andre Oppermann <andre@FreeBSD.ORG>, John Baldwin <jhb@freebsd.org>, net@freebsd.org Subject: Re: Bogus KASSERT() in tcp_output()? Message-ID: <20110201025227.J43179@maildrop.int.zabbadoz.net> In-Reply-To: <4D477289.8040901@freebsd.org> References: <201101311217.07073.jhb@freebsd.org> <4D477289.8040901@freebsd.org>
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On Tue, 1 Feb 2011, Lawrence Stewart wrote:
> On 02/01/11 04:17, John Baldwin wrote:
>> Somewhat related fallout to the bug reported on security@ recently, I think
>> this KASSERT() in tcp_output() is bogus:
>>
>>
>> KASSERT(len + hdrlen + ipoptlen == m_length(m, NULL),
>> ("%s: mbuf chain shorter than expected", __func__));
>>
>> Specifically, just a few lines earlier in tcp_output() we set the packet
>> header length to just 'len + hdrlen':
>>
>> /*
>> * Put TCP length in extended header, and then
>> * checksum extended header and data.
>> */
>> m->m_pkthdr.len = hdrlen + len; /* in6_cksum() need this */
>>
>> Also, the ipoptions are stored in a separate mbuf chain in the in pcb
>> (inp_options) that is passed as a separate argument to ip_output(). Given
>> that, I would think that m_length() should not reflect ipoptlen since it
>> should not include IP options in that chain?
>>
>
> There is some relevant prior discussion on src-committers@ for r212803
> between Andre and Bjoern.
Yeah and I still have the temporary workaround from
http://p4web.freebsd.org/@@185095?ac=10
I think you are specifically refering to
http://lists.freebsd.org/pipermail/svn-src-head/2010-October/021814.html
I had been pinging people back then, but I am happy to see the
discussion about these TCP changes finally happing now. I'll have to
swap thing back in completly - it's been more than three months. Let
me see later today.
/bz
--
Bjoern A. Zeeb You have to have visions!
<ks> Going to jail sucks -- <bz> All my daemons like it!
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/jails.html
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