netdev - [PATCH] net: check the length of the data before dereferencing it

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Message-Id: <1333336250-4110-1-git-send-email-xiaosuo@gmail.com>
Date:	Mon,  2 Apr 2012 11:10:50 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	Patrick McHardy <kaber@...sh.net>,
	Pablo Neira Ayuso <pablo@...filter.org>,
	Eric Dumazet <eric.dumazet@...il.com>,
	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org,
	Changli Gao <xiaosuo@...il.com>
Subject: [PATCH] net: check the length of the data before dereferencing it

We should check the length of the data before dereferencing it when parsing
the TCP options.

Signed-off-by: Changli Gao <xiaosuo@...il.com>
---
 net/ipv4/tcp_input.c |    2 ++
 1 file changed, 2 insertions(+)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index e886e2f..5099f08 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3845,6 +3845,8 @@ void tcp_parse_options(const struct sk_buff *skb, struct tcp_options_received *o
 			length--;
 			continue;
 		default:
+			if (length < 2)
+				return;
 			opsize = *ptr++;
 			if (opsize < 2) /* "silly options" */
 				return;
--
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