From: Andrey Konovalov <andreyknvl@google.com>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
kasan-dev <kasan-dev@googlegroups.com>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] kasan: report only the first error
Date: Wed, 22 Mar 2017 18:07:32 +0100 [thread overview]
Message-ID: <CAAeHK+zAt=iim4SoU5U8cD8i_yYoC_HGVKSvBGBgEO15KdZEPg@mail.gmail.com> (raw)
In-Reply-To: <cbb22acb-1228-0f7b-c7a0-5822ea721b3f@virtuozzo.com>
On Wed, Mar 22, 2017 at 5:54 PM, Andrey Ryabinin
<aryabinin@virtuozzo.com> wrote:
> On 03/22/2017 07:34 PM, Andrey Konovalov wrote:
>> On Wed, Mar 22, 2017 at 5:06 PM, Andrey Ryabinin
>> <aryabinin@virtuozzo.com> wrote:
>>> Disable kasan after the first report. There are several reasons for this:
>>> * Single bug quite often has multiple invalid memory accesses causing
>>> storm in the dmesg.
>>> * Write OOB access might corrupt metadata so the next report will print
>>> bogus alloc/free stacktraces.
>>> * Reports after the first easily could be not bugs by itself but just side
>>> effects of the first one.
>>>
>>> Given that multiple reports only do harm, it makes sense to disable
>>> kasan after the first one. Except for the tests in lib/test_kasan.c
>>> as we obviously want to see all reports from test.
>>
>> Hi Andrey,
>>
>> Could you make it configurable via CONFIG_KASAN_SOMETHING (which can
>> default to showing only the first report)?
>
> I'd rather make this boot time configurable, but wouldn't want to without
> a good reason.
That would work for me.
>
>
>> I sometimes use KASAN to see what bad accesses a particular bug
>> causes, and seeing all of them (even knowing that they may be
>> corrupt/induced) helps a lot.
>
> I'm wondering why you need to see all reports?
To get a better picture of what are the consequences of a bug. For
example whether it leads to some bad or controllable memory
corruption. Sometimes it's easier to let KASAN track the memory
accesses then do that manually.
>
>>
>> Thanks!
>>
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next prev parent reply other threads:[~2017-03-22 17:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-22 16:06 Andrey Ryabinin
2017-03-22 16:34 ` Andrey Konovalov
2017-03-22 16:54 ` Andrey Ryabinin
2017-03-22 17:07 ` Andrey Konovalov [this message]
2017-03-22 17:33 ` Alexander Potapenko
2017-03-22 17:42 ` Dmitry Vyukov
2017-03-23 11:49 ` [PATCH v2] kasan: report only the first error by default Andrey Ryabinin
2017-03-23 12:41 ` Mark Rutland
2017-03-23 13:06 ` Andrey Ryabinin
2017-03-23 13:29 ` Mark Rutland
2017-03-23 15:44 ` [PATCH v3] " Andrey Ryabinin
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