[NETFILTER]: nf_conntrack_tcp: catch invalid state updates over ctnetlink

Invalid states can cause out-of-bound memory accesses of the state table.
Also don't insist on having a new state contained in the netlink message.

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index 62567959b66..57831c75fa9 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -1129,11 +1129,13 @@ static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
         if (err < 0)
                 return err;
 
-        if (!tb[CTA_PROTOINFO_TCP_STATE])
+        if (tb[CTA_PROTOINFO_TCP_STATE] &&
+            nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
                 return -EINVAL;
 
         write_lock_bh(&tcp_lock);
-        ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
+        if (tb[CTA_PROTOINFO_TCP_STATE])
+                ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
 
         if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
                 struct nf_ct_tcp_flags *attr =