[PATCH v7 35/43] x86: kmsan: use __msan_ string functions where possible.

Alexander Potapenko
2022-09-15T15:11:29Z

Unless stated otherwise (by explicitly calling __memcpy(), __memset() or
__memmove()) we want all string functions to call their __msan_ versions
(e.g. __msan_memcpy() instead of memcpy()), so that shadow and origin
values are updated accordingly.

Bootloader must still use the default string functions to avoid crashes.

Signed-off-by: Alexander Potapenko <glider@google.com>
---

Link: https://linux-review.googlesource.com/id/I7ca9bd6b4f5c9b9816404862ae87ca7984395f33
---
arch/x86/include/asm/string_64.h | 23 +++++++++++++++++++++--
include/linux/fortify-string.h | 2 ++
2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index 6e450827f677a..3b87d889b6e16 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -11,11 +11,23 @@
function. */

#define __HAVE_ARCH_MEMCPY 1
+#if defined(__SANITIZE_MEMORY__)
+#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);
+#endif
extern void *__memcpy(void *to, const void *from, size_t len);

#define __HAVE_ARCH_MEMSET
+#if defined(__SANITIZE_MEMORY__)
+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
@@ -55,7 +67,13 @@ static inline void *memset64(uint64_t *s, uint64_t v, size_t n)
}

#define __HAVE_ARCH_MEMMOVE
+#if defined(__SANITIZE_MEMORY__)
+#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);
@@ -64,8 +82,7 @@ char *strcpy(char *dest, const char *src);
char *strcat(char *dest, const char *src);
int strcmp(const char *cs, const char *ct);

-#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
-
+#if (defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__))
/*
* For files that not instrumented (e.g. mm/slub.c) we
* should use not instrumented version of mem* functions.
@@ -73,7 +90,9 @@ int strcmp(const char *cs, const char *ct);

#undef memcpy
#define memcpy(dst, src, len) __memcpy(dst, src, len)
+#undef memmove
#define memmove(dst, src, len) __memmove(dst, src, len)
+#undef memset
#define memset(s, c, n) __memset(s, c, n)

#ifndef __NO_FORTIFY
diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
index 3b401fa0f3746..6c8a1a29d0b63 100644
--- a/include/linux/fortify-string.h
+++ b/include/linux/fortify-string.h
@@ -285,8 +285,10 @@ __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size,
* __builtin_object_size() must be captured here to avoid evaluating argument
* side-effects further into the macro layers.
*/
+#ifndef CONFIG_KMSAN
#define memset(p, c, s) __fortify_memset_chk(p, c, s, \
__builtin_object_size(p, 0), __builtin_object_size(p, 1))
+#endif

/*
* To make sure the compiler can enforce protection against buffer overflows,
--
2.37.2.789.g6183377224-goog