+ x86-fortify-kmsan-fix-kmsan-fortify-builds.patch added to mm-hotfixes-unstable branch

+ x86-fortify-kmsan-fix-kmsan-fortify-builds.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: x86: fortify: kmsan: fix KMSAN fortify builds
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     x86-fortify-kmsan-fix-kmsan-fortify-builds.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/x86-fortify-kmsan-fix-kmsan-fortify-builds.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

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------------------------------------------------------
From: Alexander Potapenko <glider@google.com>
Subject: x86: fortify: kmsan: fix KMSAN fortify builds
Date: Mon, 24 Oct 2022 23:21:44 +0200

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: Alexander Potapenko <glider@google.com>
Reported-by: Tamas 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: Andrew Morton <akpm@linux-foundation.org>
---

 arch/x86/include/asm/string_64.h |   11 +++++++----
 include/linux/fortify-string.h   |   17 +++++++++++++++--
 include/linux/kmsan_string.h     |   21 +++++++++++++++++++++
 mm/kmsan/instrumentation.c       |    1 +
 4 files changed, 44 insertions(+), 6 deletions(-)

--- a/arch/x86/include/asm/string_64.h~x86-fortify-kmsan-fix-kmsan-fortify-builds
+++ a/arch/x86/include/asm/string_64.h
@@ -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
 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
 }
 
 #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
--- a/include/linux/fortify-string.h~x86-fortify-kmsan-fix-kmsan-fortify-builds
+++ a/include/linux/fortify-string.h
@@ -43,11 +43,24 @@ extern __kernel_size_t __underlying_strl
 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
--- /dev/null
+++ a/include/linux/kmsan_string.h
@@ -0,0 +1,21 @@
+/* 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 */
--- a/mm/kmsan/instrumentation.c~x86-fortify-kmsan-fix-kmsan-fortify-builds
+++ a/mm/kmsan/instrumentation.c
@@ -14,6 +14,7 @@
 
 #include "kmsan.h"
 #include <linux/gfp.h>
+#include <linux/kmsan_string.h>
 #include <linux/mm.h>
 #include <linux/uaccess.h>
 
_

Patches currently in -mm which might be from glider@google.com are

mm-kmsan-export-kmsan_copy_page_meta.patch
x86-purgatory-disable-kmsan-instrumentation.patch
kconfigdebug-disable-config_frame_warn-for-kmsan-by-default.patch
x86-asm-make-sure-__put_user_size-evaluates-pointer-once.patch
x86-fortify-kmsan-fix-kmsan-fortify-builds.patch