Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210804090957.12393-1-Kuan-Ying.Lee@mediatek.com> <20210804090957.12393-3-Kuan-Ying.Lee@mediatek.com>
In-Reply-To: <20210804090957.12393-3-Kuan-Ying.Lee@mediatek.com>
From:   Andrey Konovalov <andreyknvl@gmail.com>
Date:   Wed, 4 Aug 2021 14:44:22 +0200
Message-ID: <CA+fCnZd6d9yFZZBM-zPOC54ZiHGnCxV-XiYrCfbCTzzhRV8H1w@mail.gmail.com>
Subject: Re: [PATCH v3 2/2] kasan, slub: reset tag when printing address
To:     Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Cc:     Nicholas Tang <nicholas.tang@mediatek.com>,
        Andrew Yang <andrew.yang@mediatek.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Alexander Potapenko <glider@google.com>,
        Marco Elver <elver@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Chinwen Chang <chinwen.chang@mediatek.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Wed, Aug 4, 2021 at 11:10 AM Kuan-Ying Lee
<Kuan-Ying.Lee@mediatek.com> wrote:
>
> The address still includes the tags when it is printed.
> With hardware tag-based kasan enabled, we will get a
> false positive KASAN issue when we access metadata.
>
> Reset the tag before we access the metadata.
>
> Fixes: aa1ef4d7b3f6 ("kasan, mm: reset tags when accessing metadata")
> Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
> Reviewed-by: Marco Elver <elver@google.com>
> ---
>  mm/slub.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index b6c5205252eb..f77d8cd79ef7 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -576,8 +576,8 @@ static void print_section(char *level, char *text, u8 *addr,
>                           unsigned int length)
>  {
>         metadata_access_enable();
> -       print_hex_dump(level, kasan_reset_tag(text), DUMP_PREFIX_ADDRESS,
> -                       16, 1, addr, length, 1);
> +       print_hex_dump(level, text, DUMP_PREFIX_ADDRESS,
> +                       16, 1, kasan_reset_tag((void *)addr), length, 1);
>         metadata_access_disable();
>  }
>
> --
> 2.18.0

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

Thanks!