netfilter: ctnetlink: missing validation of CTA_EXPECT_ZONE attribute

This patch adds the missing validation of the CTA_EXPECT_ZONE
attribute in the ctnetlink code.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>

net/netfilter/nf_conntrack_netlink.c

@@ -1733,6 +1733,7 @@ static const struct nla_policy exp_nla_policy[CTA_EXPECT_MAX+1] = {
 	[CTA_EXPECT_TIMEOUT]	= { .type = NLA_U32 },
 	[CTA_EXPECT_ID]		= { .type = NLA_U32 },
 	[CTA_EXPECT_HELP_NAME]	= { .type = NLA_NUL_STRING },
+	[CTA_EXPECT_ZONE]	= { .type = NLA_U16 },
 };
 
 static int