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

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Message-ID: <1333336773.2325.6531.camel@edumazet-glaptop>
Date:	Mon, 02 Apr 2012 05:19:33 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Changli Gao <xiaosuo@...il.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Patrick McHardy <kaber@...sh.net>,
	Pablo Neira Ayuso <pablo@...filter.org>,
	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] net: check the length of the data before dereferencing
 it

On Mon, 2012-04-02 at 11:10 +0800, Changli Gao wrote:
> 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;

Acked-by: Eric Dumazet <eric.dumazet@...il.com>


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