linux-kernel - Re: [PATCH 1/4] x86: kmsan: Don't rename memintrinsics in uninstrumented files

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Message-ID: <CANpmjNMR5ExTdo+EiLs=_b0M=SpN_gKAZTbSZmyfWFpBh4kN-w@mail.gmail.com>
Date:   Thu, 2 Mar 2023 12:13:28 +0100
From:   Marco Elver <elver@...gle.com>
To:     Alexander Potapenko <glider@...gle.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        dave.hansen@...ux.intel.com, hpa@...or.com,
        akpm@...ux-foundation.org, dvyukov@...gle.com, nathan@...nel.org,
        ndesaulniers@...gle.com, kasan-dev@...glegroups.com,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH 1/4] x86: kmsan: Don't rename memintrinsics in
 uninstrumented files

On Wed, 1 Mar 2023 at 15:39, Alexander Potapenko <glider@...gle.com> wrote:
>
> KMSAN should be overriding calls to memset/memcpy/memmove and their

You mean that the compiler will override calls?
All supported compilers that have fsanitize=kernel-memory replace
memintrinsics with __msan_mem*() calls, right?

> __builtin_ versions in instrumented files, so there is no need to
> override them. In non-instrumented versions we are now required to
> leave memset() and friends intact, so we cannot replace them with
> __msan_XXX() functions.
>
> Cc: Kees Cook <keescook@...omium.org>
> Suggested-by: Marco Elver <elver@...gle.com>
> Signed-off-by: Alexander Potapenko <glider@...gle.com>

Other than that,

Reviewed-by: Marco Elver <elver@...gle.com>

> ---
>  arch/x86/include/asm/string_64.h | 17 -----------------
>  1 file changed, 17 deletions(-)
>
> diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
> index 888731ccf1f67..9be401d971a99 100644
> --- a/arch/x86/include/asm/string_64.h
> +++ b/arch/x86/include/asm/string_64.h
> @@ -15,22 +15,11 @@
>  #endif
>
>  #define __HAVE_ARCH_MEMCPY 1
> -#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)
> -#undef memcpy
> -#define memcpy __msan_memcpy
> -#else
>  extern void *memcpy(void *to, const void *from, size_t len);
> -#endif
>  extern void *__memcpy(void *to, const void *from, size_t len);
>
>  #define __HAVE_ARCH_MEMSET
> -#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)
> -extern void *__msan_memset(void *s, int c, size_t n);
> -#undef memset
> -#define memset __msan_memset
> -#else
>  void *memset(void *s, int c, size_t n);
> -#endif
>  void *__memset(void *s, int c, size_t n);
>
>  #define __HAVE_ARCH_MEMSET16
> @@ -70,13 +59,7 @@ static inline void *memset64(uint64_t *s, uint64_t v, size_t n)
>  }
>
>  #define __HAVE_ARCH_MEMMOVE
> -#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)
> -#undef memmove
> -void *__msan_memmove(void *dest, const void *src, size_t len);
> -#define memmove __msan_memmove
> -#else
>  void *memmove(void *dest, const void *src, size_t count);
> -#endif
>  void *__memmove(void *dest, const void *src, size_t count);
>
>  int memcmp(const void *cs, const void *ct, size_t count);
> --
> 2.39.2.722.g9855ee24e9-goog
>