From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 29 Oct 2010 17:59:40 +0000 (+0200)
Subject: netfilter: fix nf_conntrack_l4proto_register()
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=d817d29d0b37290d90b3a9e2a61162f1dbf2be4f;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git

netfilter: fix nf_conntrack_l4proto_register()

While doing __rcu annotations work on net/netfilter I found following
bug. On some arches, it is possible we publish a table while its content
is not yet committed to memory, and lockless reader can dereference wild
pointer.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
---

diff --git a/net/netfilter/nf_conntrack_proto.c b/net/netfilter/nf_conntrack_proto.c
index ed6d92958023..dc7bb74110df 100644
--- a/net/netfilter/nf_conntrack_proto.c
+++ b/net/netfilter/nf_conntrack_proto.c
@@ -292,6 +292,12 @@ int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 
 		for (i = 0; i < MAX_NF_CT_PROTO; i++)
 			proto_array[i] = &nf_conntrack_l4proto_generic;
+
+		/* Before making proto_array visible to lockless readers,
+		 * we must make sure its content is committed to memory.
+		 */
+		smp_wmb();
+
 		nf_ct_protos[l4proto->l3proto] = proto_array;
 	} else if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto] !=
 					&nf_conntrack_l4proto_generic) {