From: Eric Dumazet Date: Fri, 29 Oct 2010 17:59:40 +0000 (+0200) Subject: netfilter: fix nf_conntrack_l4proto_register() X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=d817d29d0b37290d90b3a9e2a61162f1dbf2be4f;p=deliverable%2Flinux.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 Signed-off-by: Patrick McHardy --- 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) {