From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Changli Gao <xiaosuo@gmail.com>
Cc: Patrick McHardy <kaber@trash.net>,
"David S. Miller" <davem@davemloft.net>,
netfilter-devel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH] netfilter: check the length of the data before dereferencing it
Date: Sun, 1 Apr 2012 18:43:25 +0200 [thread overview]
Message-ID: <20120401164325.GB10861@1984> (raw)
In-Reply-To: <1333290170-26898-1-git-send-email-xiaosuo@gmail.com>
On Sun, Apr 01, 2012 at 10:22:50PM +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@gmail.com>
> ---
> net/netfilter/nf_conntrack_proto_tcp.c | 4 ++++
> 1 file changed, 4 insertions(+)
> diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
> index 361eade..9e446c5 100644
> --- a/net/netfilter/nf_conntrack_proto_tcp.c
> +++ b/net/netfilter/nf_conntrack_proto_tcp.c
> @@ -404,6 +404,8 @@ static void tcp_options(const struct sk_buff *skb,
> length--;
> continue;
> default:
> + if (length < 2)
> + return;
> opsize=*ptr++;
> if (opsize < 2) /* "silly options" */
> return;
length is always multiple of 4:
int length = (tcph->doff*4) - sizeof(struct tcphdr);
next prev parent reply other threads:[~2012-04-01 16:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-01 14:22 [PATCH] netfilter: check the length of the data before dereferencing it Changli Gao
2012-04-01 16:43 ` Pablo Neira Ayuso [this message]
2012-04-01 16:55 ` Eric Dumazet
2012-04-01 17:02 ` Pablo Neira Ayuso
2012-04-02 3:05 ` Changli Gao
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