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From: Alexander Potapenko <glider@google.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Marco Elver <elver@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Will Deacon <will.deacon@arm.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Evgenii Stepanov <eugenis@google.com>,
	Branislav Rankov <Branislav.Rankov@arm.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	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>
Subject: Re: [PATCH 09/11] kasan: fix memory corruption in kasan_bitops_tags test
Date: Wed, 13 Jan 2021 13:30:22 +0100	[thread overview]
Message-ID: <CAG_fn=XfNb_tuUiGDhRAyihTQhW8RQ8zVjT+gXM_Efhw0cBg6Q@mail.gmail.com> (raw)
In-Reply-To: <CAAeHK+xbYpuipd3+Jew7=fL8Mn2J1ZzOVyzK+X6bvtLCeiGFuw@mail.gmail.com>

On Tue, Jan 12, 2021 at 9:07 PM 'Andrey Konovalov' via kasan-dev
<kasan-dev@googlegroups.com> wrote:
>
> On Tue, Jan 12, 2021 at 9:30 AM Alexander Potapenko <glider@google.com> wrote:
> >
> > On Tue, Jan 5, 2021 at 7:28 PM Andrey Konovalov <andreyknvl@google.com> wrote:
> > >
> > > Since the hardware tag-based KASAN mode might not have a redzone that
> > > comes after an allocated object (when kasan.mode=prod is enabled), the
> > > kasan_bitops_tags() test ends up corrupting the next object in memory.
> > >
> > > Change the test so it always accesses the redzone that lies within the
> > > allocated object's boundaries.
> > >
> > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > > Link: https://linux-review.googlesource.com/id/I67f51d1ee48f0a8d0fe2658c2a39e4879fe0832a
Reviewed-by: Alexander Potapenko <glider@google.com>

> > > ---
> > >  lib/test_kasan.c | 12 ++++++------
> > >  1 file changed, 6 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> > > index b67da7f6e17f..3ea52da52714 100644
> > > --- a/lib/test_kasan.c
> > > +++ b/lib/test_kasan.c
> > > @@ -771,17 +771,17 @@ static void kasan_bitops_tags(struct kunit *test)
> > >
> > >         /* This test is specifically crafted for the tag-based mode. */
> > >         if (IS_ENABLED(CONFIG_KASAN_GENERIC)) {
> > > -               kunit_info(test, "skipping, CONFIG_KASAN_SW_TAGS required");
> > > +               kunit_info(test, "skipping, CONFIG_KASAN_SW/HW_TAGS required");
> > >                 return;
> > >         }
> > >
> > > -       /* Allocation size will be rounded to up granule size, which is 16. */
> > > -       bits = kzalloc(sizeof(*bits), GFP_KERNEL);
> > > +       /* kmalloc-64 cache will be used and the last 16 bytes will be the redzone. */
> > > +       bits = kzalloc(48, GFP_KERNEL);
> >
> > I think it might make sense to call ksize() here to ensure we have
> > these spare bytes.
>
> Calling ksize() will unpoison the whole object.

Ah, that's right.

> I think it's OK to make assumptions about KASAN internals in tests. I
> would actually say that we need more tests that check such internal
> properties.

Agreed.

  reply	other threads:[~2021-01-13 12:31 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-05 18:27 [PATCH 00/11] kasan: HW_TAGS tests support and fixes Andrey Konovalov
2021-01-05 18:27 ` [PATCH 01/11] kasan: prefix exported functions with kasan_ Andrey Konovalov
2021-01-12  7:38   ` Alexander Potapenko
2021-01-12 11:19   ` Marco Elver
2021-01-05 18:27 ` [PATCH 02/11] kasan: clarify HW_TAGS impact on TBI Andrey Konovalov
2021-01-12  7:40   ` Alexander Potapenko
2021-01-12 11:38   ` Marco Elver
2021-01-05 18:27 ` [PATCH 03/11] kasan: clean up comments in tests Andrey Konovalov
2021-01-12  7:53   ` Alexander Potapenko
2021-01-12 17:55     ` Andrey Konovalov
2021-01-12 13:07   ` Marco Elver
2021-01-05 18:27 ` [PATCH 04/11] kasan: add match-all tag tests Andrey Konovalov
2021-01-12  8:04   ` Alexander Potapenko
2021-01-12 18:10     ` Andrey Konovalov
2021-01-12 13:17   ` Marco Elver
2021-01-12 18:11     ` Andrey Konovalov
2021-01-05 18:27 ` [PATCH 05/11] kasan, arm64: allow using KUnit tests with HW_TAGS mode Andrey Konovalov
2021-01-12 19:01   ` Catalin Marinas
2021-01-15 13:11     ` Andrey Konovalov
2021-01-15 15:04   ` Vincenzo Frascino
2021-01-05 18:27 ` [PATCH 06/11] kasan: rename CONFIG_TEST_KASAN_MODULE Andrey Konovalov
2021-01-12  8:09   ` Alexander Potapenko
2021-01-12 18:26     ` Andrey Konovalov
2021-01-12 13:33   ` Marco Elver
2021-01-12 18:28     ` Andrey Konovalov
2021-01-05 18:27 ` [PATCH 07/11] kasan: add compiler barriers to KUNIT_EXPECT_KASAN_FAIL Andrey Konovalov
2021-01-12  8:18   ` Alexander Potapenko
2021-01-12 19:50     ` Andrey Konovalov
2021-01-12 19:57       ` Andrey Konovalov
2021-01-12 13:34   ` Marco Elver
2021-01-05 18:27 ` [PATCH 08/11] kasan: adopt kmalloc_uaf2 test to HW_TAGS mode Andrey Konovalov
2021-01-12  8:25   ` Alexander Potapenko
2021-01-12 20:04     ` Andrey Konovalov
2021-01-12 13:39   ` Marco Elver
2021-01-12 20:05     ` Andrey Konovalov
2021-01-05 18:27 ` [PATCH 09/11] kasan: fix memory corruption in kasan_bitops_tags test Andrey Konovalov
2021-01-12  8:30   ` Alexander Potapenko
2021-01-12 20:06     ` Andrey Konovalov
2021-01-13 12:30       ` Alexander Potapenko [this message]
2021-01-12 13:55   ` Marco Elver
2021-01-05 18:27 ` [PATCH 10/11] kasan: fix bug detection via ksize for HW_TAGS mode Andrey Konovalov
2021-01-12 14:32   ` Marco Elver
2021-01-12 21:16     ` Andrey Konovalov
2021-01-12 22:54       ` Marco Elver
2021-01-05 18:27 ` [PATCH 11/11] kasan: add proper page allocator tests Andrey Konovalov
2021-01-12  8:57   ` Alexander Potapenko
2021-01-12 14:34   ` Marco Elver

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