linux-kernel - Re: [PATCH v4 3/3] kasan: Make addr_has_metadata() return true for valid addresses

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Date:   Fri, 22 Jan 2021 17:09:43 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Vincenzo Frascino <vincenzo.frascino@....com>
Cc:     Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Leon Romanovsky <leonro@...lanox.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Naresh Kamboju <naresh.kamboju@...aro.org>
Subject: Re: [PATCH v4 3/3] kasan: Make addr_has_metadata() return true for
 valid addresses

On Fri, Jan 22, 2021 at 4:57 PM Vincenzo Frascino
<vincenzo.frascino@....com> wrote:
>
> Currently, addr_has_metadata() returns true for every address.
> An invalid address (e.g. NULL) passed to the function when,
> KASAN_HW_TAGS is enabled, leads to a kernel panic.
>
> Make addr_has_metadata() return true for valid addresses only.
>
> Note: KASAN_HW_TAGS support for vmalloc will be added with a future
> patch.
>
> Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Cc: Alexander Potapenko <glider@...gle.com>
> Cc: Dmitry Vyukov <dvyukov@...gle.com>
> Cc: Leon Romanovsky <leonro@...lanox.com>
> Cc: Andrey Konovalov <andreyknvl@...gle.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@....com>
> ---
>  mm/kasan/kasan.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index cc4d9e1d49b1..8c706e7652f2 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -209,7 +209,7 @@ bool check_memory_region(unsigned long addr, size_t size, bool write,
>
>  static inline bool addr_has_metadata(const void *addr)
>  {
> -       return true;
> +       return (is_vmalloc_addr(addr) || virt_addr_valid(addr));
>  }
>
>  #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
> --
> 2.30.0
>

Reviewed-by: Andrey Konovalov <andreyknvl@...gle.com>

Thanks!