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References: <9c0210393a8da6fb6887a111a986eb50dfc1b895.1664050880.git.andreyknvl@google.com>
 <20220925100312.6bfecb122b314862ad7b2dd4@linux-foundation.org>
In-Reply-To: <20220925100312.6bfecb122b314862ad7b2dd4@linux-foundation.org>
From:   Andrey Konovalov <andreyknvl@gmail.com>
Date:   Mon, 26 Sep 2022 20:07:59 +0200
Message-ID: <CA+fCnZe3SYq1c50hKdR3eoALz+kHE2MdUkbcbG0dhUFjaKkPNw@mail.gmail.com>
Subject: Re: [PATCH mm v2] kasan: fix array-bounds warnings in tests
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     andrey.konovalov@linux.dev, Marco Elver <elver@google.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        Kees Cook <keescook@chromium.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Andrey Konovalov <andreyknvl@google.com>,
        kernel test robot <lkp@intel.com>
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On Sun, Sep 25, 2022 at 7:03 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> > --- a/mm/kasan/kasan_test.c
> > +++ b/mm/kasan/kasan_test.c
> > @@ -333,6 +333,8 @@ static void krealloc_more_oob_helper(struct kunit *test,
> >       ptr2 = krealloc(ptr1, size2, GFP_KERNEL);
> >       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);
> >
> > +     OPTIMIZER_HIDE_VAR(ptr2);
> > +
> >       /* All offsets up to size2 must be accessible. */
> >       ptr2[size1 - 1] = 'x';
> >       ptr2[size1] = 'x';
> > @@ -365,6 +367,8 @@ static void krealloc_less_oob_helper(struct kunit *test,
> >       ptr2 = krealloc(ptr1, size2, GFP_KERNEL);
> >       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);
> >
> > +     OPTIMIZER_HIDE_VAR(ptr2);
>
> What chance does a reader have of working out why this is here?  If
> "little" then a code comment would be a nice way of saving that poor
> person for having to dive into the git history.

Will add in v3. Thank you, Andrew!