From: Eric Dumazet <eric.dumazet@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
---
net/netfilter/nf_conntrack_proto.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/net/netfilter/nf_conntrack_proto.c b/net/netfilter/nf_conntrack_proto.c
index ed6d929..dc7bb74 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) {
--
1.7.1
--
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