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

From: Florian Westphal <[email-masked]>
Date: Thu, 28 Jan 2016 15:29:59 +0100

Zhouyi Zhou <[email-masked]> 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;

Can you be more specific?

h323_buffer is backend storage for skb_header_pointer, i.e.
this will error out early when we ask for more data than is available in
packet.

I don't understand how this could overflow anything.
Even assuming 64k packet we'd still have enough room in h323_buffer
for an ipv6 address, no? (we skip the l3/l4 header when extracting
packet payload).