[PATCH v6 3/6] ARM: Replace memory function for kasan

Florian Fainelli
2019-06-17T22:11:55Z

From: Andrey Ryabinin <aryabinin@virtuozzo.com>

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.

We must use __memcpy/__memset to replace memcpy/memset when we copy
.data to RAM and when we clear .bss, because kasan_early_init can't
be called before the initialization of .data and .bss.

Reported-by: Russell King - ARM Linux <linux@armlinux.org.uk>
Signed-off-by: Abbott Liu <liuwenliang@huawei.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
arch/arm/boot/compressed/decompress.c | 2 ++
arch/arm/boot/compressed/libfdt_env.h | 2 ++
arch/arm/include/asm/string.h | 17 +++++++++++++++++
arch/arm/kernel/head-common.S | 4 ++--
arch/arm/lib/memcpy.S | 3 +++
arch/arm/lib/memmove.S | 5 ++++-
arch/arm/lib/memset.S | 3 +++
7 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/arch/arm/boot/compressed/decompress.c b/arch/arm/boot/compressed/decompress.c
index aa075d8372ea..3794fae5f818 100644
--- a/arch/arm/boot/compressed/decompress.c
+++ b/arch/arm/boot/compressed/decompress.c
@@ -47,8 +47,10 @@ extern char * strchrnul(const char *, int);
#endif

#ifdef CONFIG_KERNEL_XZ
+#ifndef CONFIG_KASAN
#define memmove memmove
#define memcpy memcpy
+#endif
#include "../../../../lib/decompress_unxz.c"
#endif

diff --git a/arch/arm/boot/compressed/libfdt_env.h b/arch/arm/boot/compressed/libfdt_env.h
index b36c0289a308..8091efc21407 100644
--- a/arch/arm/boot/compressed/libfdt_env.h
+++ b/arch/arm/boot/compressed/libfdt_env.h
@@ -19,4 +19,6 @@ typedef __be64 fdt64_t;
#define fdt64_to_cpu(x) be64_to_cpu(x)
#define cpu_to_fdt64(x) cpu_to_be64(x)

+#undef memset
+
#endif
diff --git a/arch/arm/include/asm/string.h b/arch/arm/include/asm/string.h
index 111a1d8a41dd..1f9016bbf153 100644
--- a/arch/arm/include/asm/string.h
+++ b/arch/arm/include/asm/string.h
@@ -15,15 +15,18 @@ 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 *dest, const void *src, __kernel_size_t n);

#define __HAVE_ARCH_MEMMOVE
extern void * memmove(void *, const void *, __kernel_size_t);
+extern void *__memmove(void *dest, const void *src, __kernel_size_t n);

#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 *s, int c, __kernel_size_t n);

#define __HAVE_ARCH_MEMSET32
extern void *__memset32(uint32_t *, uint32_t v, __kernel_size_t);
@@ -39,4 +42,18 @@ static inline void *memset64(uint64_t *p, uint64_t v, __kernel_size_t n)
return __memset64(p, v, n * 8, v >> 32);
}

+
+
+#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/kernel/head-common.S b/arch/arm/kernel/head-common.S
index 997b02302c31..6e3b9179806b 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -99,7 +99,7 @@ __mmap_switched:
THUMB( ldmia r4!, {r0, r1, r2, r3} )
THUMB( mov sp, r3 )
sub r2, r2, r1
- bl memcpy @ copy .data to RAM
+ bl __memcpy @ copy .data to RAM
#endif

ARM( ldmia r4!, {r0, r1, sp} )
@@ -107,7 +107,7 @@ __mmap_switched:
THUMB( mov sp, r3 )
sub r2, r1, r0
mov r1, #0
- bl memset @ clear .bss
+ bl __memset @ clear .bss

ldmia r4, {r0, r1, r2, r3}
str r9, [r0] @ Save processor ID
diff --git a/arch/arm/lib/memcpy.S b/arch/arm/lib/memcpy.S
index 4a6997bb4404..a90423194606 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 d70304cb2cd0..aabacbe33c32 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 5593a45e0a8c..c328d701b7a1 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 )
--
2.17.1