netfilter: bridge: Drops IPv6 packets if IPv6 module is not loaded

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, and the
host ip6tables will be used.

Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index d3f9592f4ff8d8435861cd95dd0d130e8fa22fbb..af7800103e51e5aee724ff314697d17ec583aeba 100644 (file)
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -496,6 +496,10 @@ static unsigned int br_nf_pre_routing(void *priv,
                if (!brnet->call_ip6tables &&
                    !br_opt_get(br, BROPT_NF_CALL_IP6TABLES))
                        return NF_ACCEPT;
+               if (!ipv6_mod_enabled()) {
+                       pr_warn_once("Module ipv6 is disabled, so call_ip6tables is not supported.");
+                       return NF_DROP;
+               }
 
                nf_bridge_pull_encap_header_rcsum(skb);
                return br_nf_pre_routing_ipv6(priv, skb, state);