netdev - [PATCH 31/53] netfilter: nf_tables: improve nft payload fast eval

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Date:   Mon, 26 Sep 2016 01:06:41 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 31/53] netfilter: nf_tables: improve nft payload fast eval

From: Liping Zhang <liping.zhang@...eadtrum.com>

There's an off-by-one issue in nft_payload_fast_eval, skb_tail_pointer
and ptr + priv->len all point to the last valid address plus 1. So if
they are equal, we can still fetch the valid data. It's unnecessary to
fall back to nft_payload_eval.

Signed-off-by: Liping Zhang <liping.zhang@...eadtrum.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nf_tables_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
index fb8b5892b5ff..36ba4e55d84e 100644
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -98,7 +98,7 @@ static bool nft_payload_fast_eval(const struct nft_expr *expr,
 
 	ptr += priv->offset;
 
-	if (unlikely(ptr + priv->len >= skb_tail_pointer(skb)))
+	if (unlikely(ptr + priv->len > skb_tail_pointer(skb)))
 		return false;
 
 	*dest = 0;
-- 
2.1.4