[PATCH 02/11] replace memory function

[Abbott Liu]

From: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>

Functions like memset/memmove/memcpy do a lot of memory accesses.
If bad pointer passed to one of these function it is important
to catch this. Compiler's instrumentation cannot do this since
these functions are written in assembly.

KASan replaces memory functions with manually instrumented variants.
Original functions declared as weak symbols so strong definitions
in mm/kasan/kasan.c could replace them. Original functions have aliases
with '__' prefix in name, so we could call non-instrumented variant
if needed.

Cc: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
Signed-off-by: Abbott Liu <liuwenliang@xxxxxxxxxx>
---
 arch/arm/include/asm/string.h | 18 +++++++++++++++++-
 arch/arm/lib/memcpy.S         |  3 +++
 arch/arm/lib/memmove.S        |  5 ++++-
 arch/arm/lib/memset.S         |  3 +++
 4 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/string.h b/arch/arm/include/asm/string.h
index fe1c6af..43325f8 100644
--- a/arch/arm/include/asm/string.h
+++ b/arch/arm/include/asm/string.h
@@ -14,15 +14,18 @@ extern char * strchr(const char * s, int c);
 
 #define __HAVE_ARCH_MEMCPY
 extern void * memcpy(void *, const void *, __kernel_size_t);
+extern void * __memcpy(void *, const void *, __kernel_size_t);
 
 #define __HAVE_ARCH_MEMMOVE
 extern void * memmove(void *, const void *, __kernel_size_t);
+extern void * __memmove(void *, const void *, __kernel_size_t);
 
 #define __HAVE_ARCH_MEMCHR
 extern void * memchr(const void *, int, __kernel_size_t);
 
 #define __HAVE_ARCH_MEMSET
 extern void * memset(void *, int, __kernel_size_t);
+extern void * __memset(void *, int, __kernel_size_t);
 
 #define __HAVE_ARCH_MEMSET32
 extern void *__memset32(uint32_t *, uint32_t v, __kernel_size_t);
@@ -39,7 +42,7 @@ static inline void *memset64(uint64_t *p, uint64_t v, __kernel_size_t n)
 }
 
 extern void __memzero(void *ptr, __kernel_size_t n);
-
+#ifndef CONFIG_KASAN
 #define memset(p,v,n)							\
 	({								\
 	 	void *__p = (p); size_t __n = n;			\
@@ -51,5 +54,18 @@ extern void __memzero(void *ptr, __kernel_size_t n);
 		}							\
 		(__p);							\
 	})
+#endif
+
+#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.
+ */
+
+#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)
+#endif
 
 #endif
diff --git a/arch/arm/lib/memcpy.S b/arch/arm/lib/memcpy.S
index 64111bd..79a83f8 100644
--- a/arch/arm/lib/memcpy.S
+++ b/arch/arm/lib/memcpy.S
@@ -61,6 +61,8 @@
 
 /* Prototype: void *memcpy(void *dest, const void *src, size_t n); */
 
+.weak memcpy
+ENTRY(__memcpy)
 ENTRY(mmiocpy)
 ENTRY(memcpy)
 
@@ -68,3 +70,4 @@ ENTRY(memcpy)
 
 ENDPROC(memcpy)
 ENDPROC(mmiocpy)
+ENDPROC(__memcpy)
diff --git a/arch/arm/lib/memmove.S b/arch/arm/lib/memmove.S
index 69a9d47..313db6c 100644
--- a/arch/arm/lib/memmove.S
+++ b/arch/arm/lib/memmove.S
@@ -27,12 +27,14 @@
  * occurring in the opposite direction.
  */
 
+.weak memmove
+ENTRY(__memmove)
 ENTRY(memmove)
 	UNWIND(	.fnstart			)
 
 		subs	ip, r0, r1
 		cmphi	r2, ip
-		bls	memcpy
+		bls	__memcpy
 
 		stmfd	sp!, {r0, r4, lr}
 	UNWIND(	.fnend				)
@@ -225,3 +227,4 @@ ENTRY(memmove)
 18:		backward_copy_shift	push=24	pull=8
 
 ENDPROC(memmove)
+ENDPROC(__memmove)
diff --git a/arch/arm/lib/memset.S b/arch/arm/lib/memset.S
index ed6d35d..64aa06a 100644
--- a/arch/arm/lib/memset.S
+++ b/arch/arm/lib/memset.S
@@ -16,6 +16,8 @@
 	.text
 	.align	5
 
+.weak memset
+ENTRY(__memset)
 ENTRY(mmioset)
 ENTRY(memset)
 UNWIND( .fnstart         )
@@ -135,6 +137,7 @@ UNWIND( .fnstart            )
 UNWIND( .fnend   )
 ENDPROC(memset)
 ENDPROC(mmioset)
+ENDPROC(__memset)
 
 ENTRY(__memset32)
 UNWIND( .fnstart         )
-- 
2.9.0