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Date:   Tue, 27 Aug 2019 23:58:36 +0200
From:   Florian Westphal <fw@strlen.de>
To:     David Miller <davemdavemloft!net@strlen.de>
Cc:     netfilter-devel@vger.kernel.org
Subject: Re: [PATCH v2 1/1] netfilter: nf_tables: fib: Drop IPV6 packages if
 IPv6 is disabled on boot
Message-ID: <20190827215836.GA10942@strlen.de>
References: <20190827.141950.540994003351676048.davem@davemloft.net>
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David Miller <davemdavemloft!net> wrote:
> From: Leonardo Bras <leonardo@linux.ibm.com>
> Date: Tue, 27 Aug 2019 14:34:14 -0300
> 
> > I could reproduce this bug on a host ('ipv6.disable=1') starting a
> > guest with a virtio-net interface with 'filterref' over a virtual
> > bridge. It crashes the host during guest boot (just before login).
> > 
> > By that I could understand that a guest IPv6 network traffic
> > (viavirtio-net) may cause this kernel panic.
> 
> Really this is bad and I suspected bridging to be involved somehow.

Thats a good point -- Leonardo, is the
"net.bridge.bridge-nf-call-ip6tables" sysctl on?

As much as i'd like to send a patch to remove br_netfilter, I fear
we can't even stop passing ipv6 packets up to netfilter if
ipv6.disable=1 is set because users might be using ip6tables for
bridged traffic.