[patch] netfilter: nf_tables: underflow in nft_parse_u32_check()

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 <redacted>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index b70d3ea..dd55187 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c

@@ -4423,7 +4423,7 @@ 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;
+	uint val;
 
 	val = ntohl(nla_get_be32(attr));
 	if (val > max)

2016-10-12 14:08 GMT+08:00 Dan Carpenter [off-list ref]:

I think it's better if you can convert it to follows:

 unsigned int nft_parse_u32_check(const struct nlattr *attr, int max, u32 *dest)

int nft_parse_u32_check(const struct nlattr *attr, u32 max, u32 *dest)

 {
-       int val;
+       uint val;

            u32 val;

        val = ntohl(nla_get_be32(attr));
        if (val > max)

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 <redacted>
---
v2: cosmetic change

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index b70d3ea..dd55187 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c

@@ -4423,7 +4423,7 @@ 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)

On Wed, Oct 12, 2016 at 12:14:29PM +0300, Dan Carpenter wrote:

We don't want to allow negatives here.

Applied, thanks.