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From:   Andrey Konovalov <andreyknvl@google.com>
Date:   Wed, 11 Nov 2020 19:52:09 +0100
Message-ID: <CAAeHK+wX+JPyZm2A5mDdGFCqnH6kdSBLyOZ2TnWfZnZuq_V0Bw@mail.gmail.com>
Subject: Re: [PATCH v9 21/44] kasan: kasan_non_canonical_hook only for
 software modes
To:     Alexander Potapenko <glider@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 Wed, Nov 11, 2020 at 4:09 PM Alexander Potapenko <glider@google.com> wrote:
>
> On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.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@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, 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.

In what way?