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From:   Alexander Potapenko <glider@google.com>
Date:   Tue, 12 Jan 2021 09:04:54 +0100
Message-ID: <CAG_fn=WX5rGMHKPrDVCUoTNFwygW9AP7QrVwrco1R70sZ6MqQA@mail.gmail.com>
Subject: Re: [PATCH 04/11] kasan: add match-all tag tests
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>
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On Tue, Jan 5, 2021 at 7:28 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> Add 3 new tests for tag-based KASAN modes:
>
> 1. Check that match-all pointer tag is not assigned randomly.
> 2. Check that 0xff works as a match-all pointer tag.
> 3. Check that there are no match-all memory tags.
>
> Note, that test #3 causes a significant number (255) of KASAN reports
> to be printed during execution for the SW_TAGS mode.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Link: https://linux-review.googlesource.com/id/I78f1375efafa162b37f3abcb2c5bc2f3955dfd8e
> ---
>  lib/test_kasan.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++
>  mm/kasan/kasan.h |  6 ++++
>  2 files changed, 99 insertions(+)
>
> diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> index 46e578c8e842..f1eda0bcc780 100644
> --- a/lib/test_kasan.c
> +++ b/lib/test_kasan.c
> @@ -13,6 +13,7 @@
>  #include <linux/mman.h>
>  #include <linux/module.h>
>  #include <linux/printk.h>
> +#include <linux/random.h>
>  #include <linux/slab.h>
>  #include <linux/string.h>
>  #include <linux/uaccess.h>
> @@ -790,6 +791,95 @@ static void vmalloc_oob(struct kunit *test)
>         vfree(area);
>  }
>
> +/*
> + * Check that match-all pointer tag is not assigned randomly for
> + * tag-based modes.
> + */
> +static void match_all_not_assigned(struct kunit *test)
> +{

Do we want to run this test in non-tag-based modes? Probably not?