linux-kernel - Re: [m68k:master 1174/1174] arch/m68k/include/asm/string.h:72:25: warning: '__builtin_memcpy' forming offset 8 is out of the bounds [0, 7]

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Message-ID: <CAMuHMdVzLTO-yYJJ=HqVySX6gqes9cnyspungsB5maduzNt0RA@mail.gmail.com>
Date:   Thu, 7 Mar 2019 09:30:43 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Finn Thain <fthain@...egraphics.com.au>
Cc:     Andreas Schwab <schwab@...ux-m68k.org>,
        kbuild test robot <lkp@...el.com>, kbuild-all@...org,
        linux-m68k <linux-m68k@...ts.linux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [m68k:master 1174/1174] arch/m68k/include/asm/string.h:72:25:
 warning: '__builtin_memcpy' forming offset 8 is out of the bounds [0, 7]

Hi Finn,

On Thu, Mar 7, 2019 at 3:59 AM Finn Thain <fthain@...egraphics.com.au> wrote:
> On Tue, 5 Mar 2019, Andreas Schwab wrote:
> > On Mar 05 2019, Finn Thain <fthain@...egraphics.com.au> wrote:
> >
> > > interesting that the kernel's strlen implementation in
> > > include/linux/string.h can't achieve this.
> >
> > This implementation is only available if ARCH_HAS_FORTIFY_SOURCE.
> >
>
> I see. Perhaps we could add another definition to that file:
>
> #if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE)
> ...
> #else
> __FORTIFY_INLINE __kernel_size_t strlen(const char *p)
> {
>         return __builtin_strlen(p);
> }
> #endif
>
> I didn't test that. But the following patch seems to work...
>
> diff --git a/arch/m68k/include/asm/string.h b/arch/m68k/include/asm/string.h
> index f759d944c449..3cff6b128ed3 100644
> --- a/arch/m68k/include/asm/string.h
> +++ b/arch/m68k/include/asm/string.h
> @@ -71,4 +71,6 @@ extern void *memset(void *, int, __kernel_size_t);
>  extern void *memcpy(void *, const void *, __kernel_size_t);
>  #define memcpy(d, s, n) __builtin_memcpy(d, s, n)
>
> +#define strlen(s) __builtin_strlen(s)

Shouldn't you add

    #define __HAVE_ARCH_STRLEN

here...

> +
>  #endif /* _M68K_STRING_H_ */
> diff --git a/lib/string.c b/lib/string.c
> index 38e4ca08e757..fe970f2160e5 100644
> --- a/lib/string.c
> +++ b/lib/string.c
> @@ -472,6 +472,7 @@ char *strim(char *s)
>  EXPORT_SYMBOL(strim);
>
>  #ifndef __HAVE_ARCH_STRLEN
> +#undef strlen

... so you can drop this change?

>  /**
>   * strlen - Find the length of a string
>   * @s: The string to be sized

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds