linux-kernel - Re: [PATCH v9 21/44] kasan: kasan_non_canonical

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Date:   Wed, 11 Nov 2020 16:08:55 +0100
From:   Alexander Potapenko <glider@...gle.com>
To:     Andrey Konovalov <andreyknvl@...gle.com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Marco Elver <elver@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v9 21/44] kasan: kasan_non_canonical_hook only for
 software modes

On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@...gle.com> wrote:
>
> 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@...gle.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@....com>
> Reviewed-by: Marco Elver <elver@...gle.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, bool 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 high
>   * canonical half of the address space) cause out-of-bounds shadow memory reads

Perhaps this comment also needs to be updated.

> --
> 2.29.2.222.g5d2a92d10f8-goog
>


-- 
Alexander Potapenko
Software Engineer

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