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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 1/2] netfilter: Terminate rule eval if protocol=IPv6 and ipv6 module is disabled
Date: Fri, 30 Aug 2019 15:13:53 -0300	[thread overview]
Message-ID: <20190830181354.26279-2-leonardo@linux.ibm.com> (raw)
In-Reply-To: <20190830181354.26279-1-leonardo@linux.ibm.com>

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 <leonardo@linux.ibm.com>
---
 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 <linux/netfilter/nf_tables.h>
 #include <net/netfilter/nf_tables_core.h>
 #include <net/netfilter/nf_tables.h>
+#include <net/ipv6.h>
 
 #include <net/netfilter/nft_fib.h>
 
@@ -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:
-- 
2.20.1


  reply	other threads:[~2019-08-30 18:14 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-30 18:13 [PATCH v4 0/2] Drop IPV6 packets if IPv6 is disabled on boot Leonardo Bras
2019-08-30 18:13 ` Leonardo Bras [this message]
2019-08-30 20:58   ` [PATCH v4 1/2] netfilter: Terminate rule eval if protocol=IPv6 and ipv6 module is disabled Florian Westphal
2019-09-03 16:46     ` Leonardo Bras
2019-09-03 16:49       ` Pablo Neira Ayuso
2019-09-03 16:56         ` Leonardo Bras
2019-09-03 17:05         ` Florian Westphal
2019-09-03 19:31           ` Pablo Neira Ayuso
2019-09-03 19:48             ` Florian Westphal
2019-09-03 20:19               ` Pablo Neira Ayuso
2019-09-03 20:35                 ` Florian Westphal
2019-09-03 20:55                   ` Pablo Neira Ayuso
2019-09-03 20:55   ` Pablo Neira Ayuso
2019-08-30 18:13 ` [PATCH v4 2/2] net: br_netfiler_hooks: Drops IPv6 packets if IPv6 module is not loaded Leonardo Bras
2019-08-30 20:55   ` Florian Westphal
2019-08-31  4:42     ` Leonardo Bras
2019-08-31  8:43       ` Florian Westphal

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