netdev - [PATCH 04/11] netfilter: nft_hash: validate maximum value of u32 netlink hash attribute

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Date:   Wed, 30 Nov 2016 22:57:18 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 04/11] netfilter: nft_hash: validate maximum value of u32 netlink hash attribute

From: Laura Garcia Liebana <nevola@...il.com>

Use the function nft_parse_u32_check() to fetch the value and validate
the u32 attribute into the hash len u8 field.

This patch revisits 4da449ae1df9 ("netfilter: nft_exthdr: Add size check
on u8 nft_exthdr attributes").

Fixes: cb1b69b0b15b ("netfilter: nf_tables: add hash expression")
Signed-off-by: Laura Garcia Liebana <nevola@...il.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nft_hash.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c
index baf694de3935..d5447a22275c 100644
--- a/net/netfilter/nft_hash.c
+++ b/net/netfilter/nft_hash.c
@@ -53,6 +53,7 @@ static int nft_hash_init(const struct nft_ctx *ctx,
 {
 	struct nft_hash *priv = nft_expr_priv(expr);
 	u32 len;
+	int err;
 
 	if (!tb[NFTA_HASH_SREG] ||
 	    !tb[NFTA_HASH_DREG] ||
@@ -67,8 +68,10 @@ static int nft_hash_init(const struct nft_ctx *ctx,
 	priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]);
 	priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]);
 
-	len = ntohl(nla_get_be32(tb[NFTA_HASH_LEN]));
-	if (len == 0 || len > U8_MAX)
+	err = nft_parse_u32_check(tb[NFTA_HASH_LEN], U8_MAX, &len);
+	if (err < 0)
+		return err;
+	if (len == 0)
 		return -ERANGE;
 
 	priv->len = len;
-- 
2.1.4