linux-kernel - Re: [PATCH v2 6/9] kasan: improve slab object description

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Message-ID: <CAAeHK+xnHx5fvhq158+oxMxieG7a+gG7i0MQS92DqxYGe0O=Ww@mail.gmail.com>
Date:   Mon, 6 Mar 2017 14:45:46 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:     Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 6/9] kasan: improve slab object description

On Fri, Mar 3, 2017 at 3:39 PM, Andrey Ryabinin <aryabinin@...tuozzo.com> wrote:
>
>
> On 03/03/2017 04:52 PM, Alexander Potapenko wrote:
>> On Fri, Mar 3, 2017 at 2:31 PM, Andrey Ryabinin <aryabinin@...tuozzo.com> 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.

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)

What do you think?