Commit 78a498c3 authored by Alexander Potapenko's avatar Alexander Potapenko Committed by Andrew Morton
Browse files

x86: fortify: kmsan: fix KMSAN fortify builds 

Ensure that KMSAN builds replace memset/memcpy/memmove calls with the
respective __msan_XXX functions, and that none of the macros are redefined
twice.  This should allow building kernel with both CONFIG_KMSAN and
CONFIG_FORTIFY_SOURCE.

Link: https://lkml.kernel.org/r/20221024212144.2852069-5-glider@google.com
Link: https://github.com/google/kmsan/issues/89


Signed-off-by: default avatarAlexander Potapenko <glider@google.com>
Reported-by: default avatarTamas K Lengyel <tamas.lengyel@zentific.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 59c8a02e

arch/x86/include/asm/string_64.h

+7 −4
Original line number Diff line number Diff line
@@ -10,10 +10,13 @@ 
/* Even with __builtin_ the compiler may decide to use the out of line

   function. */



#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)

#include <linux/kmsan_string.h>

#endif



#define __HAVE_ARCH_MEMCPY 1

#if defined(__SANITIZE_MEMORY__)

#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)

#undef memcpy

void *__msan_memcpy(void *dst, const void *src, size_t size);

#define memcpy __msan_memcpy

#else

extern void *memcpy(void *to, const void *from, size_t len);
@@ -21,7 +24,7 @@ extern void *memcpy(void *to, const void *from, size_t len); 
extern void *__memcpy(void *to, const void *from, size_t len);



#define __HAVE_ARCH_MEMSET

#if defined(__SANITIZE_MEMORY__)

#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)

extern void *__msan_memset(void *s, int c, size_t n);

#undef memset

#define memset __msan_memset
@@ -67,7 +70,7 @@ static inline void *memset64(uint64_t *s, uint64_t v, size_t n) 
}



#define __HAVE_ARCH_MEMMOVE

#if defined(__SANITIZE_MEMORY__)

#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)

#undef memmove

void *__msan_memmove(void *dest, const void *src, size_t len);

#define memmove __msan_memmove

include/linux/fortify-string.h

+15 −2
Original line number Diff line number Diff line
@@ -43,11 +43,24 @@ extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen); 
extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);

extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);

#else

#define __underlying_memchr	__builtin_memchr

#define __underlying_memcmp	__builtin_memcmp



#if defined(__SANITIZE_MEMORY__)

/*

 * For KMSAN builds all memcpy/memset/memmove calls should be replaced by the

 * corresponding __msan_XXX functions.

 */

#include <linux/kmsan_string.h>

#define __underlying_memcpy	__msan_memcpy

#define __underlying_memmove	__msan_memmove

#define __underlying_memset	__msan_memset

#else

#define __underlying_memcpy	__builtin_memcpy

#define __underlying_memmove	__builtin_memmove

#define __underlying_memset	__builtin_memset

#endif



#define __underlying_memchr	__builtin_memchr

#define __underlying_memcmp	__builtin_memcmp

#define __underlying_strcat	__builtin_strcat

#define __underlying_strcpy	__builtin_strcpy

#define __underlying_strlen	__builtin_strlen

include/linux/kmsan_string.h

0 → 100644
+21 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * KMSAN string functions API used in other headers.

 *

 * Copyright (C) 2022 Google LLC

 * Author: Alexander Potapenko <glider@google.com>

 *

 */

#ifndef _LINUX_KMSAN_STRING_H

#define _LINUX_KMSAN_STRING_H



/*

 * KMSAN overrides the default memcpy/memset/memmove implementations in the

 * kernel, which requires having __msan_XXX function prototypes in several other

 * headers. Keep them in one place instead of open-coding.

 */

void *__msan_memcpy(void *dst, const void *src, size_t size);

void *__msan_memset(void *s, int c, size_t n);

void *__msan_memmove(void *dest, const void *src, size_t len);



#endif /* _LINUX_KMSAN_STRING_H */

mm/kmsan/instrumentation.c

+1 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 


#include "kmsan.h"

#include <linux/gfp.h>

#include <linux/kmsan_string.h>

#include <linux/mm.h>

#include <linux/uaccess.h>