x86_64: kasan: add interceptors for memset/memmove/memcpy functions

Recently instrumentation of builtin functions calls was removed from GCC
5.0.  To check the memory accessed by such functions, userspace asan
always uses interceptors for them.

So now we should do this as well.  This patch declares
memset/memmove/memcpy as weak symbols.  In mm/kasan/kasan.c we have our
own implementation of those functions which checks memory before accessing
it.

Default memset/memmove/memcpy now now always have aliases with '__'
prefix.  For files that built without kasan instrumentation (e.g.
mm/slub.c) original mem* replaced (via #define) with prefixed variants,
cause we don't want to check memory accesses there.

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrey Konovalov <adech.fo@gmail.com>
Cc: Yuri Gribov <tetra2005@gmail.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/boot/compressed/eboot.c

@@ -13,8 +13,7 @@
 #include <asm/setup.h>
 #include <asm/desc.h>
 
-#undef memcpy			/* Use memcpy from misc.c */
+#include "../string.h"
-
 #include "eboot.h"
 
 static efi_system_table_t *sys_table;

arch/x86/boot/compressed/misc.h

@@ -7,6 +7,7 @@
  * we just keep it from happening
  */
 #undef CONFIG_PARAVIRT
+#undef CONFIG_KASAN
 #ifdef CONFIG_X86_32
 #define _ASM_X86_DESC_H 1
 #endif

arch/x86/include/asm/string_64.h

@@ -27,11 +27,12 @@ static __always_inline void *__inline_memcpy(void *to, const void *from, size_t
    function. */
 
 #define __HAVE_ARCH_MEMCPY 1
+extern void *__memcpy(void *to, const void *from, size_t len);
+
 #ifndef CONFIG_KMEMCHECK
 #if (__GNUC__ == 4 && __GNUC_MINOR__ >= 3) || __GNUC__ > 4
 extern void *memcpy(void *to, const void *from, size_t len);
 #else
-extern void *__memcpy(void *to, const void *from, size_t len);
 #define memcpy(dst, src, len)					\
 ({								\
 	size_t __len = (len);					\
@@ -53,9 +54,11 @@ extern void *__memcpy(void *to, const void *from, size_t len);
 
 #define __HAVE_ARCH_MEMSET
 void *memset(void *s, int c, size_t n);
+void *__memset(void *s, int c, size_t n);
 
 #define __HAVE_ARCH_MEMMOVE
 void *memmove(void *dest, const void *src, size_t count);
+void *__memmove(void *dest, const void *src, size_t count);
 
 int memcmp(const void *cs, const void *ct, size_t count);
 size_t strlen(const char *s);
@@ -63,6 +66,19 @@ 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__)
+
+/*
+ * For files that not instrumented (e.g. mm/slub.c) we
+ * should use not instrumented version of mem* functions.
+ */
+
+#undef memcpy
+#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 /* __KERNEL__ */
 
 #endif /* _ASM_X86_STRING_64_H */

arch/x86/kernel/x8664_ksyms_64.c

@@ -50,13 +50,19 @@ EXPORT_SYMBOL(csum_partial);
 #undef memset
 #undef memmove
 
+extern void *__memset(void *, int, __kernel_size_t);
+extern void *__memcpy(void *, const void *, __kernel_size_t);
+extern void *__memmove(void *, const void *, __kernel_size_t);
 extern void *memset(void *, int, __kernel_size_t);
 extern void *memcpy(void *, const void *, __kernel_size_t);
-extern void *__memcpy(void *, const void *, __kernel_size_t);
+extern void *memmove(void *, const void *, __kernel_size_t);
+
+EXPORT_SYMBOL(__memset);
+EXPORT_SYMBOL(__memcpy);
+EXPORT_SYMBOL(__memmove);
 
 EXPORT_SYMBOL(memset);
 EXPORT_SYMBOL(memcpy);
-EXPORT_SYMBOL(__memcpy);
 EXPORT_SYMBOL(memmove);
 
 #ifndef CONFIG_DEBUG_VIRTUAL

arch/x86/lib/memcpy_64.S

@@ -53,6 +53,8 @@
 .Lmemcpy_e_e:
 	.previous
 
+.weak memcpy
+
 ENTRY(__memcpy)
 ENTRY(memcpy)
 	CFI_STARTPROC
@@ -199,8 +201,8 @@ ENDPROC(__memcpy)
 	 * only outcome...
 	 */
 	.section .altinstructions, "a"
-	altinstruction_entry memcpy,.Lmemcpy_c,X86_FEATURE_REP_GOOD,\
+	altinstruction_entry __memcpy,.Lmemcpy_c,X86_FEATURE_REP_GOOD,\
 			     .Lmemcpy_e-.Lmemcpy_c,.Lmemcpy_e-.Lmemcpy_c
-	altinstruction_entry memcpy,.Lmemcpy_c_e,X86_FEATURE_ERMS, \
+	altinstruction_entry __memcpy,.Lmemcpy_c_e,X86_FEATURE_ERMS, \
 			     .Lmemcpy_e_e-.Lmemcpy_c_e,.Lmemcpy_e_e-.Lmemcpy_c_e
 	.previous

arch/x86/lib/memmove_64.S

@@ -24,7 +24,10 @@
  * Output:
  * rax: dest
  */
+.weak memmove
+
 ENTRY(memmove)
+ENTRY(__memmove)
 	CFI_STARTPROC
 
 	/* Handle more 32 bytes in loop */
@@ -220,4 +223,5 @@ ENTRY(memmove)
 		.Lmemmove_end_forward-.Lmemmove_begin_forward,	\
 		.Lmemmove_end_forward_efs-.Lmemmove_begin_forward_efs
 	.previous
+ENDPROC(__memmove)
 ENDPROC(memmove)

arch/x86/lib/memset_64.S

@@ -56,6 +56,8 @@
 .Lmemset_e_e:
 	.previous
 
+.weak memset
+
 ENTRY(memset)
 ENTRY(__memset)
 	CFI_STARTPROC
@@ -147,8 +149,8 @@ ENDPROC(__memset)
          * feature to implement the right patch order.
 	 */
 	.section .altinstructions,"a"
-	altinstruction_entry memset,.Lmemset_c,X86_FEATURE_REP_GOOD,\
+	altinstruction_entry __memset,.Lmemset_c,X86_FEATURE_REP_GOOD,\
-			     .Lfinal-memset,.Lmemset_e-.Lmemset_c
+			     .Lfinal-__memset,.Lmemset_e-.Lmemset_c
-	altinstruction_entry memset,.Lmemset_c_e,X86_FEATURE_ERMS, \
+	altinstruction_entry __memset,.Lmemset_c_e,X86_FEATURE_ERMS, \
-			     .Lfinal-memset,.Lmemset_e_e-.Lmemset_c_e
+			     .Lfinal-__memset,.Lmemset_e_e-.Lmemset_c_e
 	.previous

drivers/firmware/efi/libstub/efistub.h

@@ -5,6 +5,10 @@
 /* error code which can't be mistaken for valid address */
 #define EFI_ERROR	(~0UL)
 
+#undef memcpy
+#undef memset
+#undef memmove
+
 void efi_char16_printk(efi_system_table_t *, efi_char16_t *);
 
 efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg, void *__image,

mm/kasan/kasan.c

@@ -255,6 +255,35 @@ static __always_inline void check_memory_region(unsigned long addr,
 	kasan_report(addr, size, write, _RET_IP_);
 }
 
+void __asan_loadN(unsigned long addr, size_t size);
+void __asan_storeN(unsigned long addr, size_t size);
+
+#undef memset
+void *memset(void *addr, int c, size_t len)
+{
+	__asan_storeN((unsigned long)addr, len);
+
+	return __memset(addr, c, len);
+}
+
+#undef memmove
+void *memmove(void *dest, const void *src, size_t len)
+{
+	__asan_loadN((unsigned long)src, len);
+	__asan_storeN((unsigned long)dest, len);
+
+	return __memmove(dest, src, len);
+}
+
+#undef memcpy
+void *memcpy(void *dest, const void *src, size_t len)
+{
+	__asan_loadN((unsigned long)src, len);
+	__asan_storeN((unsigned long)dest, len);
+
+	return __memcpy(dest, src, len);
+}
+
 void kasan_alloc_pages(struct page *page, unsigned int order)
 {
 	if (likely(!PageHighMem(page)))