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From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Sun, 10 Sep 2017 12:55:15 +0200
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Subject: Re: [PATCH 7/7] include/linux/string.h: add the option of fortified
 string.h functions
To: Kees Cook <keescook@chromium.org>,
        Daniel Micay <danielmicay@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Mark Rutland <mark.rutland@arm.com>, Daniel Axtens <dja@axtens.net>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Chris Metcalf <cmetcalf@ezchip.com>,
        Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
        Ingo Molnar <mingo@elte.hu>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>, Arnd Bergmann <arnd@arndb.de>
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Hi Kees, Daniel,

On Mon, Jun 19, 2017 at 10:26 PM, Kees Cook <keescook@chromium.org> wrote:
> From: Daniel Micay <danielmicay@gmail.com>
>
> This adds support for compiling with a rough equivalent to the glibc
> _FORTIFY_SOURCE=1 feature, providing compile-time and runtime buffer
> overflow checks for string.h functions when the compiler determines the
> size of the source or destination buffer at compile-time.  Unlike glibc,
> it covers buffer reads in addition to writes.

[...]

> Link: http://lkml.kernel.org/r/20170526095404.20439-1-danielmicay@gmail.com
> Signed-off-by: Daniel Micay <danielmicay@gmail.com>
> Acked-by: Kees Cook <keescook@chromium.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Daniel Axtens <dja@axtens.net>
> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Chris Metcalf <cmetcalf@ezchip.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> [kees: move from -mm, add ARCH_HAS_FORTIFY_SOURCE, tweak Kconfig help]
> Signed-off-by: Kees Cook <keescook@chromium.org>

This is now commit 6974f0c4555e285a upstream.

> --- a/include/linux/string.h
> +++ b/include/linux/string.h
> @@ -187,4 +187,204 @@ static inline const char *kbasename(const char *path)
>         return tail ? tail + 1 : path;
>  }
>
> +#define __FORTIFY_INLINE extern __always_inline __attribute__((gnu_inline))

With gcc-4.1.2, I now get zillions of:

    include/linux/string.h:439: warning: ‘gnu_inline’ attribute
directive ignored

This attribute seems to be supported as of gcc 4.2?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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