linux-kernel - Re: [PATCH v3] add the option of fortified string.h functions

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Message-ID: <CAGXu5jJQpiSHVw-6OeS92i2UU+QFDeXN9Wrs-V_8YKD_fHuqNg@mail.gmail.com>
Date:   Thu, 25 May 2017 20:40:28 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Daniel Micay <danielmicay@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Mark Rutland <mark.rutland@....com>,
        Daniel Axtens <dja@...ens.net>
Subject: Re: [PATCH v3] add the option of fortified string.h functions

On Mon, May 22, 2017 at 4:10 PM, Daniel Micay <danielmicay@...il.com> wrote:
> diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
> index 733bae07fb29..3c5b26e07b85 100644
> --- a/arch/x86/include/asm/string_64.h
> +++ b/arch/x86/include/asm/string_64.h
> @@ -77,6 +77,11 @@ int strcmp(const char *cs, const char *ct);
>  #define memcpy(dst, src, len) __memcpy(dst, src, len)
>  #define memmove(dst, src, len) __memmove(dst, src, len)
>  #define memset(s, c, n) __memset(s, c, n)
> +
> +#ifndef __NO_FORTIFY
> +#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
> +#endif
> +
>  #endif
>
>  #define __HAVE_ARCH_MEMCPY_MCSAFE 1

Ah-ha, this same KASAN exclusion is missing for string_32.h, which is
what I think akpm tripped over in build tests.

-Kees

-- 
Kees Cook
Pixel Security