netdev - Re: [PATCH V2] netfilter: h323: avoid potential attack

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Message-ID: <56AA2186.1090208@cogentembedded.com>
Date:	Thu, 28 Jan 2016 17:11:18 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Zhouyi Zhou <zhouzhouyi@...il.com>, eric.dumazet@...il.com,
	pablo@...filter.org, kaber@...sh.net, kadlec@...ckhole.kfki.hu,
	davem@...emloft.net, netfilter-devel@...r.kernel.org,
	coreteam@...filter.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.or
Cc:	Zhouyi Zhou <yizhouzhou@....ac.cn>
Subject: Re: [PATCH V2] netfilter: h323: avoid potential attack

Hello.

On 1/28/2016 11:59 AM, Zhouyi Zhou wrote:

> Thanks Eric for your review and advice.
>
> I think hackers chould build a malicious h323 packet to overflow
> the pointer p which will panic during the memcpy(addr, p, len)
>
> For example, he may fabricate a very large taddr->ipAddress.ip;
>
> Signed-off-by: Zhouyi Zhou <yizhouzhou@....ac.cn>
> ---
>   net/netfilter/nf_conntrack_h323_main.c |    7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/net/netfilter/nf_conntrack_h323_main.c b/net/netfilter/nf_conntrack_h323_main.c
> index 9511af0..ccd08c5 100644
> --- a/net/netfilter/nf_conntrack_h323_main.c
> +++ b/net/netfilter/nf_conntrack_h323_main.c
> @@ -110,6 +110,7 @@ int (*nat_q931_hook) (struct sk_buff *skb,
>
>   static DEFINE_SPINLOCK(nf_h323_lock);
>   static char *h323_buffer;
> +#define CHECK_BOUND(p, n) ((void *)p + n - (void *)h323_buffer > 65536)

    You have to enclose the macro parameters in parens when used in expression.

MBR, Sergei