linux-kernel - Re: [PATCH] usercopy: ARM NOMMU has no 64-bit get

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Date:   Tue, 21 Feb 2017 21:33:26 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Hoeun Ryu <hoeun.ryu@...il.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usercopy: ARM NOMMU has no 64-bit get_user

On Tue, Feb 21, 2017 at 2:01 PM, Arnd Bergmann <arnd@...db.de> wrote:
> On a NOMMU ARM kernel, we get this link error:
>
> ERROR: "__get_user_bad" [lib/test_user_copy.ko] undefined!
>
> The problem is that the extended get_user/put_user definitions
> were only added for the noral (MMU based) case.
>
> We could add it for NOMMU as well, but it seems easier to just not
> call it, since no other code needs it.
>
> Fixes: 075c4ea5363d ("usercopy: Add tests for all get_user() sizes")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Ah, excellent, thanks! I'll get this in.

-Kees

> ---
>  lib/test_user_copy.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/lib/test_user_copy.c b/lib/test_user_copy.c
> index 4a79f2c1cd6e..361576b2cb3d 100644
> --- a/lib/test_user_copy.c
> +++ b/lib/test_user_copy.c
> @@ -30,7 +30,8 @@
>   * As there doesn't appear to be anything that can safely determine
>   * their capability at compile-time, we just have to opt-out certain archs.
>   */
> -#if BITS_PER_LONG == 64 || (!defined(CONFIG_AVR32)  &&         \
> +#if BITS_PER_LONG == 64 || (!(defined(CONFIG_ARM) && !defined(MMU)) && \
> +                           !defined(CONFIG_AVR32)  &&          \
>                             !defined(CONFIG_BLACKFIN) &&        \
>                             !defined(CONFIG_M32R) &&            \
>                             !defined(CONFIG_M68K) &&            \
> --
> 2.9.0
>



-- 
Kees Cook
Pixel Security