From: Leonardo Bras <leonardo@linux.ibm.com>
Date: Sat, 31 Aug 2019 04:40:33 +0000 (-0300)
Subject: netfilter: bridge: Drops IPv6 packets if IPv6 module is not loaded
X-Git-Tag: v5.3~5^2~48^2~4
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=48bd0d68cd4b849c0bb99dc1fb01b013ad4aa942;p=linux-block.git

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 d3f9592f4ff8..af7800103e51 100644
--- 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);