netfilter: nft_tunnel: ERSPAN_VERSION must not be null

stable inclusion
from linux-4.19.102
commit 9f19727f16fa96fa2b61b134e3a4be48d3128076

--------------------------------

[ Upstream commit 9ec22d7c ]

Fixes: af308b94 ("netfilter: nf_tables: add tunnel support")
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NLi Aichun <liaichun@huawei.com>
Reviewed-by: Nguodeqing <geffrey.guo@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

net/netfilter/nft_tunnel.c

@@ -235,6 +235,9 @@ static int nft_tunnel_obj_erspan_init(const struct nlattr *attr,
 	if (err < 0)
 		return err;
 
+	if (!tb[NFTA_TUNNEL_KEY_ERSPAN_VERSION])
+		 return -EINVAL;
+
 	version = ntohl(nla_get_be32(tb[NFTA_TUNNEL_KEY_ERSPAN_VERSION]));
 	switch (version) {
 	case ERSPAN_VERSION: