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From:   Alexander Potapenko <glider@google.com>
Date:   Wed, 11 Nov 2020 16:08:55 +0100
Message-ID: <CAG_fn=VXhK0d__FkNdhdquy9F4VmB64_6eJQOQBRecy2oL6huQ@mail.gmail.com>
Subject: Re: [PATCH v9 21/44] kasan: kasan_non_canonical_hook only for
 software modes
To:     Andrey Konovalov <andreyknvl@google.com>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Marco Elver <elver@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.com> w=
rote:
>
> This is a preparatory commit for the upcoming addition of a new hardware
> tag-based (MTE-based) KASAN mode.
>
> kasan_non_canonical_hook() is only applicable to KASAN modes that use
> shadow memory, and won't be needed for hardware tag-based KASAN.
>
> No functional changes for software modes.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Reviewed-by: Marco Elver <elver@google.com>
> ---
> Change-Id: Icc9f5ef100a2e86f3a4214a0c3131a68266181b2
> ---
>  mm/kasan/report.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 5d5733831ad7..594bad2a3a5e 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -403,7 +403,8 @@ bool kasan_report(unsigned long addr, size_t size, bo=
ol is_write,
>         return ret;
>  }
>
> -#ifdef CONFIG_KASAN_INLINE
> +#if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && =
\
> +       defined(CONFIG_KASAN_INLINE)
>  /*
>   * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the hig=
h
>   * canonical half of the address space) cause out-of-bounds shadow memor=
y reads

Perhaps this comment also needs to be updated.

> --
> 2.29.2.222.g5d2a92d10f8-goog
>


--=20
Alexander Potapenko
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