linux-kernel - Re: [PATCH v15 2/4] kasan: allow architectures to provide an outline readiness check

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Date:   Wed, 23 Jun 2021 19:25:12 +1000
From:   Daniel Axtens <dja@...ens.net>
To:     Andrey Konovalov <andreyknvl@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Marco Elver <elver@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linuxppc-dev@...ts.ozlabs.org, christophe.leroy@...roup.eu,
        aneesh.kumar@...ux.ibm.com, bsingharora@...il.com
Subject: Re: [PATCH v15 2/4] kasan: allow architectures to provide an
 outline readiness check

>> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
>> index 10177cc26d06..0ad615f3801d 100644
>> --- a/mm/kasan/common.c
>> +++ b/mm/kasan/common.c
>> @@ -331,6 +331,10 @@ static inline bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
>>         u8 tag;
>>         void *tagged_object;
>>
>> +       /* Bail if the arch isn't ready */
>
> This comment brings no value. The fact that we bail is clear from the
> following line. The comment should explain why we bail.
>
>> +       if (!kasan_arch_is_ready())
>> +               return false;

Fair enough, I've just dropped the comments as I don't think there's
really a lot of scope for the generic/core comment to explain why a
particular architecture might not be ready.

> Have you considered including these checks into the high-level
> wrappers in include/linux/kasan.h? Would that work?

I don't think those wrappers will catch the outline check functions
like __asan_load*, which also need guarding.

Kind regards,
Daniel