From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: KASAN poisoning for skb linear data Date: Thu, 8 Mar 2018 07:43:21 -0800 Message-ID: <20180308074321.5d57bbda@xeon-e3> References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: David Miller , Willem de Bruijn , Eric Dumazet , netdev , LKML , kasan-dev , Cong Wang , andreyknvl To: Dmitry Vyukov Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, 8 Mar 2018 10:20:44 +0100 Dmitry Vyukov wrote: > On Mon, Jan 15, 2018 at 3:15 PM, Dmitry Vyukov wrote: > > Hi, > > > > As far as I understand pskb_may_pull() plays important role in packet > > parsing for all protocols. And we did custom fragmentation of packets > > emitted via tun (IFF_NAPI_FRAGS). However, it seems that it does not > > give any results (bugs found), and I think the reason for this is that > > linear data is rounded up and is usually quite large. So if a parsing > > function does pskb_may_pull(1), or does not do it at all, it can > > usually access more and it will go unnoticed. KASAN has an ability to > > do custom poisoning: it can poison/unpoison any memory range, and then > > detect any reads/writes to that range. What do you think about adding > > custom KASAN poisoning to pskb_may_pull() and switching it to > > non-eager mode (pull only what was requested) under KASAN? Do you > > think it has potential for finding important bugs? What amount of work > > is this? > > Filed https://bugzilla.kernel.org/show_bug.cgi?id=199055 for this so > it's not get lost. Linux kernel networking does really use kernel bugzilla. It is a conduit for bug reports but not used for managing most issues.