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* [PATCH] netfilter: nft_hash: fix hash overflow validation
@ 2016-09-13  8:21 Laura Garcia Liebana
  2016-09-13  8:48 ` Pablo Neira Ayuso
  0 siblings, 1 reply; 2+ messages in thread
From: Laura Garcia Liebana @ 2016-09-13  8:21 UTC (permalink / raw)
  To: netfilter-devel

The overflow validation in the init() function establishes that the
maximum value that the hash could reach is less than U32_MAX, which is
likely to be true.

The fix detects the overflow when the maximum hash value is less than
the offset itself.

Fixes: 70ca767ea1b2 ("netfilter: nft_hash: Add hash offset value")

Reported-by: Liping Zhang <liping.zhang@spreadtrum.com>
Signed-off-by: Laura Garcia Liebana <nevola@gmail.com>
---
 net/netfilter/nft_hash.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c
index bd12f7a..09473b4 100644
--- a/net/netfilter/nft_hash.c
+++ b/net/netfilter/nft_hash.c
@@ -76,7 +76,7 @@ static int nft_hash_init(const struct nft_ctx *ctx,
 	if (priv->modulus <= 1)
 		return -ERANGE;
 
-	if (priv->offset + priv->modulus - 1 < U32_MAX)
+	if (priv->offset + priv->modulus - 1 < priv->offset)
 		return -EOVERFLOW;
 
 	priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED]));
-- 
2.8.1


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] netfilter: nft_hash: fix hash overflow validation
  2016-09-13  8:21 [PATCH] netfilter: nft_hash: fix hash overflow validation Laura Garcia Liebana
@ 2016-09-13  8:48 ` Pablo Neira Ayuso
  0 siblings, 0 replies; 2+ messages in thread
From: Pablo Neira Ayuso @ 2016-09-13  8:48 UTC (permalink / raw)
  To: Laura Garcia Liebana; +Cc: netfilter-devel

On Tue, Sep 13, 2016 at 10:21:46AM +0200, Laura Garcia Liebana wrote:
> The overflow validation in the init() function establishes that the
> maximum value that the hash could reach is less than U32_MAX, which is
> likely to be true.
> 
> The fix detects the overflow when the maximum hash value is less than
> the offset itself.

Applied.

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2016-09-13  8:21 [PATCH] netfilter: nft_hash: fix hash overflow validation Laura Garcia Liebana
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