From: Florian Westphal <fw@strlen.de>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Denys Fedoryshchenko <nuclearcat@nuclearcat.com>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
Pablo Neira Ayuso <pablo@netfilter.org>,
Patrick McHardy <kaber@trash.net>,
Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
linux-kernel@vger.kernel.org
Subject: Re: KASAN, xt_TCPMSS finally found nasty use-after-free bug? 4.10.8
Date: Sun, 2 Apr 2017 13:45:45 +0200 [thread overview]
Message-ID: <20170402114545.GA31804@breakpoint.cc> (raw)
In-Reply-To: <1491132259.10124.3.camel@edumazet-glaptop3.roam.corp.google.com>
Eric Dumazet <eric.dumazet@gmail.com> wrote:
> - for (i = sizeof(struct tcphdr); i <= tcp_hdrlen - TCPOLEN_MSS; i += optlen(opt, i)) {
> + for (i = sizeof(struct tcphdr); i < tcp_hdrlen - TCPOLEN_MSS; i += optlen(opt, i)) {
> if (opt[i] == TCPOPT_MSS && opt[i+1] == TCPOLEN_MSS) {
> u_int16_t oldmss;
maybe I am low on caffeeine but this looks fine, for tcp header with
only tcpmss this boils down to "20 <= 24 - 4" so we acccess offsets 20-23 which seems ok.
next prev parent reply other threads:[~2017-04-02 11:45 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-02 7:43 KASAN, xt_TCPMSS finally found nasty use-after-free bug? 4.10.8 Denys Fedoryshchenko
2017-04-02 11:24 ` Eric Dumazet
2017-04-02 11:45 ` Florian Westphal [this message]
2017-04-02 11:51 ` Denys Fedoryshchenko
2017-04-02 11:54 ` Eric Dumazet
2017-04-02 12:19 ` Eric Dumazet
2017-04-02 12:25 ` Denys Fedoryshchenko
2017-04-02 12:32 ` Eric Dumazet
2017-04-02 16:52 ` Denys Fedoryshchenko
2017-04-02 17:14 ` Eric Dumazet
2017-04-02 17:26 ` Eric Dumazet
2017-04-03 8:10 ` Denys Fedoryshchenko
2017-04-03 12:09 ` Eric Dumazet
2017-04-03 12:14 ` Denys Fedoryshchenko
2017-04-03 12:24 ` Eric Dumazet
2017-04-03 17:55 ` [PATCH net] netfilter: xt_TCPMSS: add more sanity tests on tcph->doff Eric Dumazet
2017-04-08 20:24 ` Pablo Neira Ayuso
2017-04-20 18:14 ` Denys Fedoryshchenko
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