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From:   Marco Elver <elver@google.com>
Date:   Thu, 13 Jun 2019 15:00:09 +0200
Message-ID: <CANpmjNNMmSHvP+tzod=WeoDp6jsxGsDKV5cXiTr3F9fxEMasaw@mail.gmail.com>
Subject: Re: [PATCH v4 1/3] lib/test_kasan: Add bitops tests
To:     Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Dmitry Vyukov <dvyukov@google.com>,
        Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@google.com>,
        Mark Rutland <mark.rutland@arm.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Jonathan Corbet <corbet@lwn.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        kasan-dev <kasan-dev@googlegroups.com>
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On Thu, 13 Jun 2019 at 14:49, Andrey Ryabinin <aryabinin@virtuozzo.com> wrote:
>
>
>
> On 6/13/19 3:30 PM, Marco Elver wrote:
> > This adds bitops tests to the test_kasan module. In a follow-up patch,
> > support for bitops instrumentation will be added.
> >
> > Signed-off-by: Marco Elver <elver@google.com>
> > Acked-by: Mark Rutland <mark.rutland@arm.com>
> > ---
>
> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
>
>
>
>
> > +static noinline void __init kasan_bitops(void)
> > +{
> > +     /*
> > +      * Allocate 1 more byte, which causes kzalloc to round up to 16-bytes;
> > +      * this way we do not actually corrupt other memory, in case
> > +      * instrumentation is not working as intended.
>
> This sound like working instrumentation somehow save us from corrupting memory. In fact it doesn't,
> it only reports corruption.

Thanks, I removed the confusing wording. Sent v5.

> > +      */
> > +     long *bits = kzalloc(sizeof(*bits) + 1, GFP_KERNEL);
> > +     if (!bits)
> > +             return;
> > +
>
> --
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