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Subject: Re: [PATCH v9 3/4] kasan: Add report for async mode
To:     Andrey Konovalov <andreyknvl@google.com>
Cc:     Linux ARM <linux-arm-kernel@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Marco Elver <elver@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>
References: <20210126134603.49759-1-vincenzo.frascino@arm.com>
 <20210126134603.49759-4-vincenzo.frascino@arm.com>
 <CAAeHK+xAbsX9Zz4aKXToNTrbgrrYck23ohGJHXvgeSTyZy=Odg@mail.gmail.com>
From:   Vincenzo Frascino <vincenzo.frascino@arm.com>
Message-ID: <77de8e48-6f68-bf27-0bed-02e49b69a12d@arm.com>
Date:   Fri, 29 Jan 2021 17:48:12 +0000
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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");
>> +       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