netfilter: nf_tables: underflow in nft_parse_u32_check()

commit 09525a09ad3099efd9ba49b0b90bddc350d6b53a upstream.

We don't want to allow negatives here.

Fixes: 36b701fae12a ('netfilter: nf_tables: validate maximum value of u32 netlink attributes')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index a8093ab11b7c6e61eb9cadbfcef218369e088e3c..39210b8370c6c181ee8e5dbcd3bc1d9f03529040 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -3725,7 +3725,7 @@ static int nf_tables_check_loops(const struct nft_ctx *ctx,
  */
 unsigned int nft_parse_u32_check(const struct nlattr *attr, int max, u32 *dest)
 {
-       int val;
+       u32 val;
 
        val = ntohl(nla_get_be32(attr));
        if (val > max)