Re: [PATCH v9 3/4] kasan: Add report for async mode

From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>,
	Marco Elver <elver@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Evgenii Stepanov <eugenis@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	kasan-dev <kasan-dev@googlegroups.com>,
	Alexander Potapenko <glider@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Will Deacon <will@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v9 3/4] kasan: Add report for async mode
Date: Fri, 29 Jan 2021 18:01:32 +0000	[thread overview]
Message-ID: <7da762df-6df3-e526-bec1-dc770709c00c@arm.com> (raw)
In-Reply-To: <CAAeHK+xMWXpfLs6HuKN73e0p61nm+QrZO1-oXphJpjZprKQVKg@mail.gmail.com>

On 1/29/21 5:56 PM, Andrey Konovalov wrote:
> On Fri, Jan 29, 2021 at 6:44 PM Vincenzo Frascino
> <vincenzo.frascino@arm.com> wrote:
>>
>>
>>
>> On 1/29/21 5:40 PM, Andrey Konovalov wrote:
>>> On Tue, Jan 26, 2021 at 2:46 PM Vincenzo Frascino
>>> <vincenzo.frascino@arm.com> wrote:
>>>>
>>>> KASAN provides an asynchronous mode of execution.
>>>>
>>>> Add reporting functionality for this mode.
>>>>
>>>> Cc: Dmitry Vyukov <dvyukov@google.com>
>>>> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
>>>> Cc: Alexander Potapenko <glider@google.com>
>>>> Cc: Andrey Konovalov <andreyknvl@google.com>
>>>> Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
>>>> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
>>>> ---
>>>>  include/linux/kasan.h |  6 ++++++
>>>>  mm/kasan/report.c     | 13 +++++++++++++
>>>>  2 files changed, 19 insertions(+)
>>>>
>>>> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
>>>> index bb862d1f0e15..b6c502dad54d 100644
>>>> --- a/include/linux/kasan.h
>>>> +++ b/include/linux/kasan.h
>>>> @@ -360,6 +360,12 @@ static inline void *kasan_reset_tag(const void *addr)
>>>>
>>>>  #endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS*/
>>>>
>>>> +#ifdef CONFIG_KASAN_HW_TAGS
>>>> +
>>>> +void kasan_report_async(void);
>>>> +
>>>> +#endif /* CONFIG_KASAN_HW_TAGS */
>>>> +
>>>>  #ifdef CONFIG_KASAN_SW_TAGS
>>>>  void __init kasan_init_sw_tags(void);
>>>>  #else
>>>> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
>>>> index 87b271206163..69bad9c01aed 100644
>>>> --- a/mm/kasan/report.c
>>>> +++ b/mm/kasan/report.c
>>>> @@ -360,6 +360,19 @@ void kasan_report_invalid_free(void *object, unsigned long ip)
>>>>         end_report(&flags, (unsigned long)object);
>>>>  }
>>>>
>>>> +#ifdef CONFIG_KASAN_HW_TAGS
>>>> +void kasan_report_async(void)
>>>> +{
>>>> +       unsigned long flags;
>>>> +
>>>> +       start_report(&flags);
>>>> +       pr_err("BUG: KASAN: invalid-access\n");
>>>> +       pr_err("Asynchronous mode enabled: no access details available\n");
> 
> Could you also add an empty line here before the stack trace while at it?
> 

Sure no problem.

>>>> +       dump_stack();
>>>> +       end_report(&flags);
>>>
>>> This conflicts with "kasan: use error_report_end tracepoint" that's in mm.
>>>
>>> I suggest to call end_report(&flags, 0) here and check addr !=0 in
>>> end_report() before calling trace_error_report_end().
>>>
>>
>> I just noticed and about to post a rebased version with end_report(&flags, 0).
>>
>>
>>>> +}
>>>> +#endif /* CONFIG_KASAN_HW_TAGS */
>>>> +
>>>>  static void __kasan_report(unsigned long addr, size_t size, bool is_write,
>>>>                                 unsigned long ip)
>>>>  {
>>>> --
>>>> 2.30.0
>>>>
>>
>> --
>> Regards,
>> Vincenzo

-- 
Regards,
Vincenzo

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