Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754041AbdCFSOY (ORCPT ); Mon, 6 Mar 2017 13:14:24 -0500 Received: from mail-wm0-f41.google.com ([74.125.82.41]:37842 "EHLO mail-wm0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753261AbdCFSOQ (ORCPT ); Mon, 6 Mar 2017 13:14:16 -0500 MIME-Version: 1.0 In-Reply-To: References: <20170302134851.101218-1-andreyknvl@google.com> <20170302134851.101218-7-andreyknvl@google.com> <2bbe7bdc-8842-8ec0-4b5a-6a8dce39216d@virtuozzo.com> <576aeb81-9408-13fa-041d-a6bd1e2cf895@virtuozzo.com> From: Andrey Konovalov Date: Mon, 6 Mar 2017 18:16:47 +0100 Message-ID: Subject: Re: [PATCH v2 6/9] kasan: improve slab object description To: Andrey Ryabinin Cc: Alexander Potapenko , Dmitry Vyukov , kasan-dev , Linux Memory Management List , LKML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2659 Lines: 73 On Mon, Mar 6, 2017 at 6:05 PM, Andrey Konovalov wrote: > On Mon, Mar 6, 2017 at 5:12 PM, Andrey Ryabinin wrote: >> On 03/06/2017 04:45 PM, Andrey Konovalov wrote: >>> On Fri, Mar 3, 2017 at 3:39 PM, Andrey Ryabinin wrote: >>>> >>>> >>>> On 03/03/2017 04:52 PM, Alexander Potapenko wrote: >>>>> On Fri, Mar 3, 2017 at 2:31 PM, Andrey Ryabinin wrote: >>>>>> On 03/02/2017 04:48 PM, Andrey Konovalov wrote: >>>>>>> Changes slab object description from: >>>>>>> >>>>>>> Object at ffff880068388540, in cache kmalloc-128 size: 128 >>>>>>> >>>>>>> to: >>>>>>> >>>>>>> The buggy address belongs to the object at ffff880068388540 >>>>>>> which belongs to the cache kmalloc-128 of size 128 >>>>>>> The buggy address is located 123 bytes inside of >>>>>>> 128-byte region [ffff880068388540, ffff8800683885c0) >>>>>>> >>>>>>> Makes it more explanatory and adds information about relative offset >>>>>>> of the accessed address to the start of the object. >>>>>>> >>>>>> >>>>>> I don't think that this is an improvement. You replaced one simple line with a huge >>>>>> and hard to parse text without giving any new/useful information. >>>>>> Except maybe offset, it useful sometimes, so wouldn't mind adding it to description. >>>>> Agreed. >>>>> How about: >>>>> =========== >>>>> Access 123 bytes inside of 128-byte region [ffff880068388540, ffff8800683885c0) >>>>> Object at ffff880068388540 belongs to the cache kmalloc-128 >>>>> =========== >>>>> ? >>>>> >>>> >>>> I would just add the offset in the end: >>>> Object at ffff880068388540, in cache kmalloc-128 size: 128 accessed at offset y >>> >>> Access can be inside or outside the object, so it's better to >>> specifically say that. >>> >> >> That what access offset and object's size tells us. >> >> >>> I think we can do (basically what Alexander suggested): >>> >>> Object at ffff880068388540 belongs to the cache kmalloc-128 of size 128 >>> Access 123 bytes inside of 128-byte region [ffff880068388540, ffff8800683885c0) >> >> This is just wrong and therefore very confusing. The message says that we access 123 bytes, >> while in fact we access x-bytes at offset 123. IOW 123 sounds like access size here not the offset. > > What about > > Object at ffff880068388540 belongs to cache kmalloc-128 of size 128 > Accessed address is 123 bytes inside of [ffff880068388540, ffff8800683885c0) > > ? Another alternative: Accessed address is 123 bytes inside of [ffff880068388540, ffff8800683885c0) Object belongs to cache kmalloc-128 of size 128 > >> >> >>> What do you think? >>> >> >> Not better.