netfilter: nft_range: validate operation netlink attribute

Use nft_parse_u32_check() to make sure we don't get a value over the
unsigned 8-bit integer. Moreover, make sure this value doesn't go over
the two supported range comparison modes.

Fixes: 9286c2eb1fda ("netfilter: nft_range: validate operation netlink attribute")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_range.c

@@ -59,6 +59,7 @@ static int nft_range_init(const struct nft_ctx *ctx, const struct nft_expr *expr
 	struct nft_range_expr *priv = nft_expr_priv(expr);
 	struct nft_data_desc desc_from, desc_to;
 	int err;
+	u32 op;
 
 	err = nft_data_init(NULL, &priv->data_from, sizeof(priv->data_from),
 			    &desc_from, tb[NFTA_RANGE_FROM_DATA]);
@@ -80,7 +81,20 @@ static int nft_range_init(const struct nft_ctx *ctx, const struct nft_expr *expr
 	if (err < 0)
 		goto err2;
 
-	priv->op  = ntohl(nla_get_be32(tb[NFTA_RANGE_OP]));
+	err = nft_parse_u32_check(tb[NFTA_RANGE_OP], U8_MAX, &op);
+	if (err < 0)
+		goto err2;
+
+	switch (op) {
+	case NFT_RANGE_EQ:
+	case NFT_RANGE_NEQ:
+		break;
+	default:
+		err = -EINVAL;
+		goto err2;
+	}
+
+	priv->op  = op;
 	priv->len = desc_from.len;
 	return 0;
 err2: