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

[Pablo Neira Ayuso]

From: Laura Garcia Liebana <nev...@gmail.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 <nev...@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.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