[PATCH nf-next] netfilter: nf_tables: remove useless U8_MAX validation

[PATCH nf-next] netfilter: nf_tables: remove useless U8_MAX validation

[Liping Zhang]

From: Liping Zhang <zlpnobody@gmail.com>

After call nft_data_init, size is already validated and desc.len will
not exceed the sizeof(struct nft_data), i.e. 16 bytes. So it will never
exceed U8_MAX.

Furthermore, in nft_immediate_init, we forget to call nft_data_uninit
when desc.len exceeds U8_MAX, although this will not happen, but it's
a logical mistake.

Now remove these redundant validation introduced by commit 36b701fae12a
("netfilter: nf_tables: validate maximum value of u32 netlink attributes")

Signed-off-by: Liping Zhang <zlpnobody@gmail.com>
---
 net/netfilter/nft_cmp.c       | 3 ---
 net/netfilter/nft_immediate.c | 3 ---
 2 files changed, 6 deletions(-)

diff --git a/net/netfilter/nft_cmp.c b/net/netfilter/nft_cmp.c
index 2e53739..e25b35d 100644
--- a/net/netfilter/nft_cmp.c
+++ b/net/netfilter/nft_cmp.c
@@ -84,9 +84,6 @@ static int nft_cmp_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 	if (err < 0)
 		return err;
 
-	if (desc.len > U8_MAX)
-		return -ERANGE;
-
 	priv->op  = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
 	priv->len = desc.len;
 	return 0;
diff --git a/net/netfilter/nft_immediate.c b/net/netfilter/nft_immediate.c
index d17018f..4528ade 100644
--- a/net/netfilter/nft_immediate.c
+++ b/net/netfilter/nft_immediate.c
@@ -54,9 +54,6 @@ static int nft_immediate_init(const struct nft_ctx *ctx,
 	if (err < 0)
 		return err;
 
-	if (desc.len > U8_MAX)
-		return -ERANGE;
-
 	priv->dlen = desc.len;
 
 	priv->dreg = nft_parse_register(tb[NFTA_IMMEDIATE_DREG]);
-- 
2.5.5

Re: [PATCH nf-next] netfilter: nf_tables: remove useless U8_MAX validation

[Pablo Neira Ayuso]

On Sat, Oct 29, 2016 at 09:56:27PM +0800, Liping Zhang wrote:
> From: Liping Zhang <zlpnobody@gmail.com>
> 
> After call nft_data_init, size is already validated and desc.len will
> not exceed the sizeof(struct nft_data), i.e. 16 bytes. So it will never
> exceed U8_MAX.
> 
> Furthermore, in nft_immediate_init, we forget to call nft_data_uninit
> when desc.len exceeds U8_MAX, although this will not happen, but it's
> a logical mistake.
> 
> Now remove these redundant validation introduced by commit 36b701fae12a
> ("netfilter: nf_tables: validate maximum value of u32 netlink attributes")

Applied, thanks.