[PATCH 9/9] ARM: Add KASan support
Ahmad Fatoum
a.fatoum at pengutronix.de
Tue Feb 9 04:25:57 EST 2021
Hello Sascha,
On 18.09.20 10:45, Sascha Hauer wrote:
> This adds KASan support to the ARM architecture. What we are doing is:
>
> * Add __no_sanitize_address attribute to various lowlevel functions
> which do not run in a proper C environment
> * Add non-instrumented variants of memset/memcpy (prefixed with '__')
> * make original memcpy/memset weak symbols so strong definitions in
> lib/kasan/common.c can replace them
> * Use non-instrumented memcpy in early functions
> * call kasan_init()
>
> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
> ---
> arch/arm/Kconfig | 1 +
> arch/arm/cpu/Makefile | 2 ++
> arch/arm/cpu/common.c | 2 +-
> arch/arm/cpu/setupc.S | 6 +++---
Shouldn't you've touched setupc_64.S here as well?
> arch/arm/cpu/start.c | 7 +++++--
> arch/arm/include/asm/string.h | 2 ++
> arch/arm/lib32/barebox.lds.S | 4 +++-
> arch/arm/lib32/memcpy.S | 3 +++
> arch/arm/lib32/memset.S | 4 +++-
> arch/arm/lib64/string.c | 26 +++++++++++++++++++++-----
> 10 files changed, 44 insertions(+), 13 deletions(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 95fd8ecfe7..57ead9a783 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -4,6 +4,7 @@ config ARM
> select HAS_CACHE
> select HAVE_CONFIGURABLE_TEXT_BASE if !RELOCATABLE
> select HAVE_IMAGE_COMPRESSION
> + select HAVE_ARCH_KASAN
> default y
>
> config ARM_LINUX
> diff --git a/arch/arm/cpu/Makefile b/arch/arm/cpu/Makefile
> index f7f9c30415..e7a6e3e6fb 100644
> --- a/arch/arm/cpu/Makefile
> +++ b/arch/arm/cpu/Makefile
> @@ -9,6 +9,7 @@ AFLAGS_hyp.o :=-Wa,-march=armv7-a -Wa,-mcpu=all
> AFLAGS_hyp.pbl.o :=-Wa,-march=armv7-a -Wa,-mcpu=all
>
> obj-y += start.o entry.o entry_ll$(S64).o
> +KASAN_SANITIZE_start.o := n
>
> pbl-$(CONFIG_BOARD_ARM_GENERIC_DT) += board-dt-2nd.o
> pbl-$(CONFIG_BOARD_ARM_GENERIC_DT_AARCH64) += board-dt-2nd-aarch64.o
> @@ -51,3 +52,4 @@ pbl-y += entry.o entry_ll$(S64).o
> pbl-y += uncompress.o
>
> obj-pbl-y += common.o sections.o
> +KASAN_SANITIZE_common.o := n
> diff --git a/arch/arm/cpu/common.c b/arch/arm/cpu/common.c
> index 33f148fc0e..8cfcc8f6ce 100644
> --- a/arch/arm/cpu/common.c
> +++ b/arch/arm/cpu/common.c
> @@ -120,7 +120,7 @@ void relocate_to_current_adr(void)
> dstart += sizeof(*rel);
> }
>
> - memset(dynsym, 0, (unsigned long)dynend - (unsigned long)dynsym);
> + __memset(dynsym, 0, (unsigned long)dynend - (unsigned long)dynsym);
> #else
> #error "Architecture not specified"
> #endif
> diff --git a/arch/arm/cpu/setupc.S b/arch/arm/cpu/setupc.S
> index 8ae7c89a2c..55aa105b21 100644
> --- a/arch/arm/cpu/setupc.S
> +++ b/arch/arm/cpu/setupc.S
> @@ -21,12 +21,12 @@ ENTRY(setup_c)
> ldr r2,=__bss_start
> sub r2, r2, r0
> add r1, r0, r4
> - bl memcpy /* memcpy(_text, _text + offset, __bss_start - _text) */
> + bl __memcpy /* memcpy(_text, _text + offset, __bss_start - _text) */
> 1: ldr r0, =__bss_start
> mov r1, #0
> ldr r2, =__bss_stop
> sub r2, r2, r0
> - bl memset /* clear bss */
> + bl __memset /* clear bss */
> bl sync_caches_for_execution
> sub lr, r5, r4 /* adjust return address to new location */
> pop {r4, r5}
> @@ -67,7 +67,7 @@ ENTRY(relocate_to_adr)
> sub r7, r7, r1 /* sub address where we are actually running */
> add r7, r7, r0 /* add address where we are going to run */
>
> - bl memcpy /* copy binary */
> + bl __memcpy /* copy binary */
>
> bl sync_caches_for_execution
>
> diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
> index aeca459cb1..f48f5beea8 100644
> --- a/arch/arm/cpu/start.c
> +++ b/arch/arm/cpu/start.c
> @@ -15,6 +15,7 @@
> #include <asm/unaligned.h>
> #include <asm/cache.h>
> #include <asm/mmu.h>
> +#include <linux/kasan.h>
> #include <memory.h>
> #include <uncompress.h>
> #include <malloc.h>
> @@ -135,7 +136,7 @@ static int barebox_memory_areas_init(void)
> }
> device_initcall(barebox_memory_areas_init);
>
> -__noreturn void barebox_non_pbl_start(unsigned long membase,
> +__noreturn __no_sanitize_address void barebox_non_pbl_start(unsigned long membase,
> unsigned long memsize, void *boarddata)
> {
> unsigned long endmem = membase + memsize;
> @@ -233,6 +234,8 @@ __noreturn void barebox_non_pbl_start(unsigned long membase,
> pr_debug("initializing malloc pool at 0x%08lx (size 0x%08lx)\n",
> malloc_start, malloc_end - malloc_start);
>
> + kasan_init(membase, memsize, malloc_start - (memsize >> KASAN_SHADOW_SCALE_SHIFT));
> +
> mem_malloc_init((void *)malloc_start, (void *)malloc_end - 1);
>
> if (IS_ENABLED(CONFIG_BOOTM_OPTEE))
> @@ -259,7 +262,7 @@ void start(unsigned long membase, unsigned long memsize, void *boarddata);
> * First function in the uncompressed image. We get here from
> * the pbl. The stack already has been set up by the pbl.
> */
> -void NAKED __section(.text_entry) start(unsigned long membase,
> +void NAKED __no_sanitize_address __section(.text_entry) start(unsigned long membase,
> unsigned long memsize, void *boarddata)
> {
> barebox_non_pbl_start(membase, memsize, boarddata);
> diff --git a/arch/arm/include/asm/string.h b/arch/arm/include/asm/string.h
> index 435647abda..fb577cfcd5 100644
> --- a/arch/arm/include/asm/string.h
> +++ b/arch/arm/include/asm/string.h
> @@ -5,8 +5,10 @@
>
> #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_MEMSET
> extern void *memset(void *, int, __kernel_size_t);
> +extern void *__memset(void *, int, __kernel_size_t);
>
> #endif
>
> diff --git a/arch/arm/lib32/barebox.lds.S b/arch/arm/lib32/barebox.lds.S
> index ed279279a2..54d9b3e381 100644
> --- a/arch/arm/lib32/barebox.lds.S
> +++ b/arch/arm/lib32/barebox.lds.S
> @@ -77,7 +77,9 @@ SECTIONS
> _sdata = .;
>
> . = ALIGN(4);
> - .data : { *(.data*) }
> + .data : { *(.data*)
> + CONSTRUCTORS
> + }
>
> .barebox_imd : { BAREBOX_IMD }
>
> diff --git a/arch/arm/lib32/memcpy.S b/arch/arm/lib32/memcpy.S
> index 5123691ca9..0fcdaa88e6 100644
> --- a/arch/arm/lib32/memcpy.S
> +++ b/arch/arm/lib32/memcpy.S
> @@ -56,9 +56,12 @@
>
> /* Prototype: void *memcpy(void *dest, const void *src, size_t n); */
>
> +.weak memcpy
> ENTRY(memcpy)
> +ENTRY(__memcpy)
>
> #include "copy_template.S"
>
> +ENDPROC(__memcpy)
> ENDPROC(memcpy)
>
> diff --git a/arch/arm/lib32/memset.S b/arch/arm/lib32/memset.S
> index c4d2672038..6079dd89f6 100644
> --- a/arch/arm/lib32/memset.S
> +++ b/arch/arm/lib32/memset.S
> @@ -15,6 +15,8 @@
> .text
> .align 5
>
> +.weak memset
> +ENTRY(__memset)
> ENTRY(memset)
> ands r3, r0, #3 @ 1 unaligned?
> mov ip, r0 @ preserve r0 as return value
> @@ -121,4 +123,4 @@ ENTRY(memset)
> add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3))
> b 1b
> ENDPROC(memset)
> -
> +ENDPROC(__memset)
> diff --git a/arch/arm/lib64/string.c b/arch/arm/lib64/string.c
> index cb26331527..a2cf09e58e 100644
> --- a/arch/arm/lib64/string.c
> +++ b/arch/arm/lib64/string.c
> @@ -5,18 +5,34 @@
> void *__arch_memset(void *dst, int c, __kernel_size_t size);
> void *__arch_memcpy(void * dest, const void *src, size_t count);
>
> -void *memset(void *dst, int c, __kernel_size_t size)
> +static void *_memset(void *dst, int c, __kernel_size_t size)
> {
> if (likely(get_cr() & CR_M))
> return __arch_memset(dst, c, size);
>
> - return __default_memset(dst, c, size);
> + return __nokasan_default_memset(dst, c, size);
> }
>
> -void *memcpy(void * dest, const void *src, size_t count)
> +void __weak *memset(void *dst, int c, __kernel_size_t size)
> +{
> + return _memset(dst, c, size);
> +}
> +
> +void *__memset(void *dst, int c, __kernel_size_t size)
> + __alias(_memset);
> +
> +static void *_memcpy(void * dest, const void *src, size_t count)
> {
> if (likely(get_cr() & CR_M))
> return __arch_memcpy(dest, src, count);
>
> - return __default_memcpy(dest, src, count);
> -}
> \ No newline at end of file
> + return __nokasan_default_memcpy(dest, src, count);
> +}
> +
> +void __weak *memcpy(void * dest, const void *src, size_t count)
> +{
> + return _memcpy(dest, src, count);
> +}
> +
> +void *__memcpy(void * dest, const void *src, size_t count)
> + __alias(_memcpy);
>
--
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