Re: [PATCH v4 3/5] kasan: Add report for async mode

From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Andrey Konovalov <andreyknvl@google.com>,
	Mark Rutland <mark.rutland@arm.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Marco Elver <elver@google.com>,
	kasan-dev <kasan-dev@googlegroups.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Alexander Potapenko <glider@google.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Dmitry Vyukov <dvyukov@google.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Will Deacon <will@kernel.org>,
	Evgenii Stepanov <eugenis@google.com>
Subject: Re: [PATCH v4 3/5] kasan: Add report for async mode
Date: Wed, 20 Jan 2021 14:46:44 +0000	[thread overview]
Message-ID: <d9ee1147-be64-4910-aca5-6b83f1c71895@arm.com> (raw)
In-Reply-To: <CAAeHK+wcWk_URtGROUc1VLR4PjVQChCUpSLFya9DNTytQP2mVg@mail.gmail.com>

On 1/19/21 6:12 PM, Andrey Konovalov wrote:
> On Tue, Jan 19, 2021 at 3:46 PM Mark Rutland <mark.rutland@arm.com> wrote:
>>
>> Given there's no information available, I think it's simpler and
>> preferable to handle the logging separately, as is done for
>> kasan_report_invalid_free(). For example, we could do something roughly
>> like:
>>
>> void kasan_report_async(void)
>> {
>>         unsigned long flags;
>>
>>         start_report(&flags);
>>         pr_err("BUG: KASAN: Tag mismatch detected asynchronously\n");
> 
> "BUG: KASAN: invalid-access"
>

Ok, I will do in v5. It looks more uniform with what we have for the sync exception.

> It also might make sense to pass the ip, even though it's not exactly
> related to the access:
> 

I would like to avoid to add a builtin for something that has not a real meaning
as you are correctly pointing out.

> pr_err("BUG: KASAN: invalid-access in %pS\n", (void *)ip);
> 
> Up to you.
> 
>>         pr_err("KASAN: no fault information available\n");
> 
> pr_err("Asynchronous mode enabled: no access details available\n");
> 
>>         dump_stack();
>>         end_report(&flags);
>> }
> 
> This approach with a dedicated function is better. Thanks, Mark!
> 
> Please put it next to kasan_report_invalid_free().
> 

Will do in v5.

Thanks!

-- 
Regards,
Vincenzo

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