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From:   Leonardo Bras <leonardo@linux.ibm.com>
To:     netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
        bridge@lists.linux-foundation.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     Leonardo Bras <leonardo@linux.ibm.com>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Jozsef Kadlecsik <kadlec@netfilter.org>,
        Florian Westphal <fw@strlen.de>,
        Roopa Prabhu <roopa@cumulusnetworks.com>,
        Nikolay Aleksandrov <nikolay@cumulusnetworks.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH v4 2/2] net: br_netfiler_hooks: Drops IPv6 packets if IPv6 module is not loaded
Date:   Fri, 30 Aug 2019 15:13:54 -0300
Message-Id: <20190830181354.26279-3-leonardo@linux.ibm.com>
In-Reply-To: <20190830181354.26279-1-leonardo@linux.ibm.com>
References: <20190830181354.26279-1-leonardo@linux.ibm.com>
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A kernel panic can happen if a host has disabled IPv6 on boot and have to
process guest packets (coming from a bridge) using it's ip6tables.

IPv6 packets need to be dropped if the IPv6 module is not loaded.

Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com>
---
 net/bridge/br_netfilter_hooks.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index d3f9592f4ff8..5e8693730df1 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -493,6 +493,8 @@ static unsigned int br_nf_pre_routing(void *priv,
 	brnet = net_generic(state->net, brnf_net_id);
 	if (IS_IPV6(skb) || is_vlan_ipv6(skb, state->net) ||
 	    is_pppoe_ipv6(skb, state->net)) {
+		if (!ipv6_mod_enabled())
+			return NF_DROP;
 		if (!brnet->call_ip6tables &&
 		    !br_opt_get(br, BROPT_NF_CALL_IP6TABLES))
 			return NF_ACCEPT;
-- 
2.20.1