From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vc0-f178.google.com (mail-vc0-f178.google.com [209.85.220.178]) by kanga.kvack.org (Postfix) with ESMTP id 4618E6B0035 for ; Thu, 10 Jul 2014 15:48:47 -0400 (EDT) Received: by mail-vc0-f178.google.com with SMTP id ij19so148458vcb.23 for ; Thu, 10 Jul 2014 12:48:46 -0700 (PDT) Received: from mail-vc0-x22b.google.com (mail-vc0-x22b.google.com [2607:f8b0:400c:c03::22b]) by mx.google.com with ESMTPS id b5si94511vdj.25.2014.07.10.12.48.45 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 10 Jul 2014 12:48:46 -0700 (PDT) Received: by mail-vc0-f171.google.com with SMTP id id10so161235vcb.2 for ; Thu, 10 Jul 2014 12:48:45 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <53BEB77A.6020003@intel.com> 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> Date: Thu, 10 Jul 2014 23:48:45 +0400 Message-ID: Subject: Re: [RFC/PATCH RESEND -next 01/21] Add kernel address sanitizer infrastructure. From: Andrey Ryabinin Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen 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 2014-07-10 19:55 GMT+04:00 Dave Hansen : > On 07/10/2014 05:12 AM, Andrey Ryabinin wrote: >> On 07/10/14 00:26, Dave Hansen wrote: >>> On 07/09/2014 04:29 AM, Andrey Ryabinin wrote: >>>> Address sanitizer dedicates 1/8 of the low memory to the shadow memory and uses direct >>>> mapping with a scale and offset to translate a memory address to its corresponding >>>> shadow address. >>>> >>>> Here is function to translate address to corresponding shadow address: >>>> >>>> unsigned long kasan_mem_to_shadow(unsigned long addr) >>>> { >>>> return ((addr - PAGE_OFFSET) >> KASAN_SHADOW_SCALE_SHIFT) >>>> + kasan_shadow_start; >>>> } >>> >>> 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? > > addr_is_in_mem() is a pretty bad name for what it's doing. :) > > I'd probably call it something like kasan_tracks_vaddr(). > Agree > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org -- Best regards, Andrey Ryabinin -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org