diff --git a/net/ipv4/netfilter/nf_nat_l3proto_ipv4.c b/net/ipv4/netfilter/nf_nat_l3proto_ipv4.c
index 2687db015b6f1b..fa2ba7c500e411 100644
--- a/net/ipv4/netfilter/nf_nat_l3proto_ipv4.c
+++ b/net/ipv4/netfilter/nf_nat_l3proto_ipv4.c
@@ -215,6 +215,7 @@ int nf_nat_icmp_reply_translation(struct sk_buff *skb,
 
 	/* Change outer to look like the reply to an incoming packet */
 	nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
+	target.dst.protonum = IPPROTO_ICMP;
 	if (!nf_nat_ipv4_manip_pkt(skb, 0, &target, manip))
 		return 0;
 
diff --git a/net/ipv4/netfilter/nf_nat_snmp_basic_main.c b/net/ipv4/netfilter/nf_nat_snmp_basic_main.c
index a0aa13bcabda09..0a8a60c1bf9af1 100644
--- a/net/ipv4/netfilter/nf_nat_snmp_basic_main.c
+++ b/net/ipv4/netfilter/nf_nat_snmp_basic_main.c
@@ -105,6 +105,8 @@ static void fast_csum(struct snmp_ctx *ctx, unsigned char offset)
 int snmp_version(void *context, size_t hdrlen, unsigned char tag,
 		 const void *data, size_t datalen)
 {
+	if (datalen != 1)
+		return -EINVAL;
 	if (*(unsigned char *)data > 1)
 		return -ENOTSUPP;
 	return 1;
@@ -114,8 +116,11 @@ int snmp_helper(void *context, size_t hdrlen, unsigned char tag,
 		const void *data, size_t datalen)
 {
 	struct snmp_ctx *ctx = (struct snmp_ctx *)context;
-	__be32 *pdata = (__be32 *)data;
+	__be32 *pdata;
 
+	if (datalen != 4)
+		return -EINVAL;
+	pdata = (__be32 *)data;
 	if (*pdata == ctx->from) {
 		pr_debug("%s: %pI4 to %pI4\n", __func__,
 			 (void *)&ctx->from, (void *)&ctx->to);
diff --git a/net/ipv6/netfilter/nf_nat_l3proto_ipv6.c b/net/ipv6/netfilter/nf_nat_l3proto_ipv6.c
index 23022447eb497e..7a41ee3c11b4d0 100644
--- a/net/ipv6/netfilter/nf_nat_l3proto_ipv6.c
+++ b/net/ipv6/netfilter/nf_nat_l3proto_ipv6.c
@@ -226,6 +226,7 @@ int nf_nat_icmpv6_reply_translation(struct sk_buff *skb,
 	}
 
 	nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
+	target.dst.protonum = IPPROTO_ICMPV6;
 	if (!nf_nat_ipv6_manip_pkt(skb, 0, &target, manip))
 		return 0;