linux-kernel - Re: [PATCH 45/46] kasan, lto: remove extra BUILD_BUG() in memory_is

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Message-ID: <CA+fCnZfBa+MBiAYPOh_djkEcoDY652pViznDQnqX708VaxuTOg@mail.gmail.com>
Date:   Sat, 26 Nov 2022 18:07:49 +0100
From:   Andrey Konovalov <andreyknvl@...il.com>
To:     "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
Cc:     linux-kernel@...r.kernel.org, Martin Liska <mliska@...e.cz>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        Jiri Slaby <jslaby@...e.cz>
Subject: Re: [PATCH 45/46] kasan, lto: remove extra BUILD_BUG() in memory_is_poisoned

On Mon, Nov 14, 2022 at 12:45 PM Jiri Slaby (SUSE) <jirislaby@...nel.org> wrote:
>
> From: Martin Liska <mliska@...e.cz>
>
> The function memory_is_poisoned() can handle any size which can be
> propagated by LTO later on. So we can end up with a constant that is not
> handled in the switch. Thus just break and call memory_is_poisoned_n()
> which handles arbitrary size to avoid build errors with gcc LTO.
>
> Cc: Andrey Ryabinin <ryabinin.a.a@...il.com>
> Cc: Alexander Potapenko <glider@...gle.com>
> Cc: Andrey Konovalov <andreyknvl@...il.com>
> Cc: Dmitry Vyukov <dvyukov@...gle.com>
> Cc: Vincenzo Frascino <vincenzo.frascino@....com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: kasan-dev@...glegroups.com
> Cc: linux-mm@...ck.org
> Signed-off-by: Martin Liska <mliska@...e.cz>
> Signed-off-by: Jiri Slaby <jslaby@...e.cz>
> ---
>  mm/kasan/generic.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index d8b5590f9484..d261f83c6687 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -152,7 +152,7 @@ static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
>                 case 16:
>                         return memory_is_poisoned_16(addr);
>                 default:
> -                       BUILD_BUG();
> +                       break;
>                 }
>         }
>
> --
> 2.38.1
>

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