From 88209141392a4a2521a2f67c13d7db5e84efbb58 Mon Sep 17 00:00:00 2001 From: Leonardo Bras Date: Fri, 30 Aug 2019 15:13:53 -0300 Subject: [PATCH] netfilter: nft_fib_netdev: Terminate rule eval if protocol=IPv6 and ipv6 module is disabled If IPv6 is disabled on boot (ipv6.disable=1), but nft_fib_inet ends up dealing with a IPv6 packet, it causes a kernel panic in fib6_node_lookup_1(), crashing in bad_page_fault. The panic is caused by trying to deference a very low address (0x38 in ppc64le), due to ipv6.fib6_main_tbl = NULL. BUG: Kernel NULL pointer dereference at 0x00000038 The kernel panic was reproduced in a host that disabled IPv6 on boot and have to process guest packets (coming from a bridge) using it's ip6tables. Terminate rule evaluation when packet protocol is IPv6 but the ipv6 module is not loaded. Signed-off-by: Leonardo Bras Acked-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_fib_netdev.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/netfilter/nft_fib_netdev.c b/net/netfilter/nft_fib_netdev.c index 2cf3f32fe6d2..a2e726ae7f07 100644 --- a/net/netfilter/nft_fib_netdev.c +++ b/net/netfilter/nft_fib_netdev.c @@ -14,6 +14,7 @@ #include #include #include +#include #include @@ -34,6 +35,8 @@ static void nft_fib_netdev_eval(const struct nft_expr *expr, } break; case ETH_P_IPV6: + if (!ipv6_mod_enabled()) + break; switch (priv->result) { case NFT_FIB_RESULT_OIF: case NFT_FIB_RESULT_OIFNAME: