From: Florian Westphal <fw@strlen.de>
To: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org, Pablo Neira Ayuso <pablo@netfilter.org>,
Florian Westphal <fw@strlen.de>,
netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
syzbot+0346441ae0545cfcea3a@syzkaller.appspotmail.com,
syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH nf] netfilter: drop template ct when conntrack is skipped.
Date: Thu, 22 Mar 2018 12:16:19 +0100 [thread overview]
Message-ID: <20180322111619.GA8867@breakpoint.cc> (raw)
In-Reply-To: <7d4cd8cddda45ba93066e8f977aed5d16d220a67.1521713327.git.pabeni@redhat.com>
Paolo Abeni <pabeni@redhat.com> wrote:
> The ipv4 nf_ct code currently skips the nf_conntrak_in() call
> for fragmented packets. As a results later matches/target can end
> up manipulating template ct entry instead of 'real' ones.
>
> Exploiting the above, syzbot found a way to trigger the following
> splat:
>
> WARNING: CPU: 1 PID: 4242 at net/netfilter/xt_cluster.c:55
> xt_cluster_mt+0x6c1/0x840 net/netfilter/xt_cluster.c:127
> Kernel panic - not syncing: panic_on_warn set ...
Right, template has l3 protocol 0.
> Instead of adding checks for template ct on every target/match
> manipulating skb->_nfct, simply drop the template ct when skipping
> nf_conntrack_in().
Fixes: 7b4fdf77a450ec ("netfilter: don't track fragmented packets")
Acked-by: Florian Westphal <fw@strlen.de>
next prev parent reply other threads:[~2018-03-22 11:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-22 10:08 [PATCH nf] netfilter: drop template ct when conntrack is skipped Paolo Abeni
2018-03-22 11:16 ` Florian Westphal [this message]
2018-03-22 11:56 ` Pablo Neira Ayuso
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