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

[Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>]

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@ict.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