netfilter: nft_hash: validate maximum value of u32 netlink hash attribute

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@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files 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;