From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f42.google.com (mail-pa0-f42.google.com [209.85.220.42]) by kanga.kvack.org (Postfix) with ESMTP id D3CF96B0035 for ; Thu, 10 Jul 2014 16:04:58 -0400 (EDT) Received: by mail-pa0-f42.google.com with SMTP id lj1so103059pab.1 for ; Thu, 10 Jul 2014 13:04:58 -0700 (PDT) Received: from mga02.intel.com (mga02.intel.com. [134.134.136.20]) by mx.google.com with ESMTP id ot3si44610pdb.480.2014.07.10.13.04.56 for ; Thu, 10 Jul 2014 13:04:57 -0700 (PDT) Message-ID: <53BEF1E5.2000502@intel.com> Date: Thu, 10 Jul 2014 13:04:53 -0700 From: Dave Hansen MIME-Version: 1.0 Subject: Re: [RFC/PATCH RESEND -next 01/21] Add kernel address sanitizer infrastructure. References: <1404905415-9046-1-git-send-email-a.ryabinin@samsung.com> <1404905415-9046-2-git-send-email-a.ryabinin@samsung.com> <53BDA568.5030607@intel.com> <53BE8333.6060404@samsung.com> <53BEB77A.6020003@intel.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrey Ryabinin Cc: Andrey Ryabinin , linux-kernel@vger.kernel.org, Dmitry Vyukov , Konstantin Serebryany , Alexey Preobrazhensky , Andrey Konovalov , Yuri Gribov , Konstantin Khlebnikov , Sasha Levin , Michal Marek , Russell King , Thomas Gleixner , Ingo Molnar , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-kbuild@vger.kernel.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org, linux-mm@kvack.org On 07/10/2014 12:48 PM, Andrey Ryabinin wrote: >>>> How does this interact with vmalloc() addresses or those from a kmap()? >>>> >>> It's used only for lowmem: >>> >>> static inline bool addr_is_in_mem(unsigned long addr) >>> { >>> return likely(addr >= PAGE_OFFSET && addr < (unsigned long)high_memory); >>> } >> >> That's fine, and definitely covers the common cases. Could you make >> sure to call this out explicitly? Also, there's nothing to _keep_ this >> approach working for things out of the direct map, right? It would just >> be a matter of updating the shadow memory to have entries for the other >> virtual address ranges. > > Why do you want shadow for things out of the direct map? If you want > to catch use-after-free in vmalloc than DEBUG_PAGEALLOC will be > enough. If you want catch out-of-bounds in vmalloc you don't need > anything, because vmalloc allocates guarding hole in the end. Or do > you want something else? That's all true for page-size accesses. Address sanitizer's biggest advantage over using the page tables is that it can do checks at sub-page granularity. But, we don't have any APIs that I can think of that _care_ about email@kvack.org