[patch 03/12] kasan: remove redundant config option

Andrew Morton
2021-04-16T22:46:03Z

From: Walter Wu <walter-zh.wu@mediatek.com>
Subject: kasan: remove redundant config option

CONFIG_KASAN_STACK and CONFIG_KASAN_STACK_ENABLE both enable KASAN stack
instrumentation, but we should only need one config, so that we remove
CONFIG_KASAN_STACK_ENABLE and make CONFIG_KASAN_STACK workable. see [1].

When enable KASAN stack instrumentation, then for gcc we could do no
prompt and default value y, and for clang prompt and default value n.

This patch fixes the following compilation warning:

include/linux/kasan.h:333:30: warning: 'CONFIG_KASAN_STACK' is not defined, evaluates to 0 [-Wundef]

[1]: https://bugzilla.kernel.org/show_bug.cgi?id=210221

[akpm@linux-foundation.org: fix merge snafu]
Link: https://lkml.kernel.org/r/20210226012531.29231-1-walter-zh.wu@mediatek.com
Fixes: d9b571c885a8 ("kasan: fix KASAN_STACK dependency for HW_TAGS")
Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

arch/arm64/kernel/sleep.S | 2 +-
arch/x86/kernel/acpi/wakeup_64.S | 2 +-
include/linux/kasan.h | 2 +-
lib/Kconfig.kasan | 9 ++-------
mm/kasan/common.c | 2 +-
mm/kasan/kasan.h | 2 +-
mm/kasan/report_generic.c | 2 +-
scripts/Makefile.kasan | 10 ++++++++--
security/Kconfig.hardening | 4 ++--
9 files changed, 18 insertions(+), 17 deletions(-)

--- a/arch/arm64/kernel/sleep.S~kasan-remove-redundant-config-option
+++ a/arch/arm64/kernel/sleep.S
@@ -134,7 +134,7 @@ SYM_FUNC_START(_cpu_resume)
*/
bl cpu_do_resume

-#if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN) && defined(CONFIG_KASAN_STACK)
mov x0, sp
bl kasan_unpoison_task_stack_below
#endif
--- a/arch/x86/kernel/acpi/wakeup_64.S~kasan-remove-redundant-config-option
+++ a/arch/x86/kernel/acpi/wakeup_64.S
@@ -115,7 +115,7 @@ SYM_FUNC_START(do_suspend_lowlevel)
movq pt_regs_r14(%rax), %r14
movq pt_regs_r15(%rax), %r15

-#if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN) && defined(CONFIG_KASAN_STACK)
/*
* The suspend path may have poisoned some areas deeper in the stack,
* which we now need to unpoison.
--- a/include/linux/kasan.h~kasan-remove-redundant-config-option
+++ a/include/linux/kasan.h
@@ -330,7 +330,7 @@ static inline bool kasan_check_byte(cons

#endif /* CONFIG_KASAN */

-#if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN) && defined(CONFIG_KASAN_STACK)
void kasan_unpoison_task_stack(struct task_struct *task);
#else
static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
--- a/lib/Kconfig.kasan~kasan-remove-redundant-config-option
+++ a/lib/Kconfig.kasan
@@ -138,9 +138,10 @@ config KASAN_INLINE

endchoice

-config KASAN_STACK_ENABLE
+config KASAN_STACK
bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST
depends on KASAN_GENERIC || KASAN_SW_TAGS
+ default y if CC_IS_GCC
help
The LLVM stack address sanitizer has a know problem that
causes excessive stack usage in a lot of functions, see
@@ -154,12 +155,6 @@ config KASAN_STACK_ENABLE
CONFIG_COMPILE_TEST. On gcc it is assumed to always be safe
to use and enabled by default.

-config KASAN_STACK
- int
- depends on KASAN_GENERIC || KASAN_SW_TAGS
- default 1 if KASAN_STACK_ENABLE || CC_IS_GCC
- default 0
-
config KASAN_SW_TAGS_IDENTIFY
bool "Enable memory corruption identification"
depends on KASAN_SW_TAGS
--- a/mm/kasan/common.c~kasan-remove-redundant-config-option
+++ a/mm/kasan/common.c
@@ -63,7 +63,7 @@ void __kasan_unpoison_range(const void *
kasan_unpoison(address, size);
}

-#if CONFIG_KASAN_STACK
+#ifdef CONFIG_KASAN_STACK
/* Unpoison the entire stack for a task. */
void kasan_unpoison_task_stack(struct task_struct *task)
{
--- a/mm/kasan/kasan.h~kasan-remove-redundant-config-option
+++ a/mm/kasan/kasan.h
@@ -231,7 +231,7 @@ void *kasan_find_first_bad_addr(void *ad
const char *kasan_get_bug_type(struct kasan_access_info *info);
void kasan_metadata_fetch_row(char *buffer, void *row);

-#if defined(CONFIG_KASAN_GENERIC) && CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN_GENERIC) && defined(CONFIG_KASAN_STACK)
void kasan_print_address_stack_frame(const void *addr);
#else
static inline void kasan_print_address_stack_frame(const void *addr) { }
--- a/mm/kasan/report_generic.c~kasan-remove-redundant-config-option
+++ a/mm/kasan/report_generic.c
@@ -128,7 +128,7 @@ void kasan_metadata_fetch_row(char *buff
memcpy(buffer, kasan_mem_to_shadow(row), META_BYTES_PER_ROW);
}

-#if CONFIG_KASAN_STACK
+#ifdef CONFIG_KASAN_STACK
static bool __must_check tokenize_frame_descr(const char **frame_descr,
char *token, size_t max_tok_len,
unsigned long *value)
--- a/scripts/Makefile.kasan~kasan-remove-redundant-config-option
+++ a/scripts/Makefile.kasan
@@ -4,6 +4,12 @@ KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SH

cc-param = $(call cc-option, -mllvm -$(1), $(call cc-option, --param $(1)))

+ifdef CONFIG_KASAN_STACK
+ stack_enable := 1
+else
+ stack_enable := 0
+endif
+
ifdef CONFIG_KASAN_GENERIC

ifdef CONFIG_KASAN_INLINE
@@ -27,7 +33,7 @@ else
CFLAGS_KASAN := $(CFLAGS_KASAN_SHADOW) \
$(call cc-param,asan-globals=1) \
$(call cc-param,asan-instrumentation-with-call-threshold=$(call_threshold)) \
- $(call cc-param,asan-stack=$(CONFIG_KASAN_STACK)) \
+ $(call cc-param,asan-stack=$(stack_enable)) \
$(call cc-param,asan-instrument-allocas=1)
endif

@@ -42,7 +48,7 @@ else
endif

CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
- $(call cc-param,hwasan-instrument-stack=$(CONFIG_KASAN_STACK)) \
+ $(call cc-param,hwasan-instrument-stack=$(stack_enable)) \
$(call cc-param,hwasan-use-short-granules=0) \
$(instrumentation_flags)

--- a/security/Kconfig.hardening~kasan-remove-redundant-config-option
+++ a/security/Kconfig.hardening
@@ -64,7 +64,7 @@ choice
config GCC_PLUGIN_STRUCTLEAK_BYREF
bool "zero-init structs passed by reference (strong)"
depends on GCC_PLUGINS
- depends on !(KASAN && KASAN_STACK=1)
+ depends on !(KASAN && KASAN_STACK)
select GCC_PLUGIN_STRUCTLEAK
help
Zero-initialize any structures on the stack that may
@@ -82,7 +82,7 @@ choice
config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
bool "zero-init anything passed by reference (very strong)"
depends on GCC_PLUGINS
- depends on !(KASAN && KASAN_STACK=1)
+ depends on !(KASAN && KASAN_STACK)
select GCC_PLUGIN_STRUCTLEAK
help
Zero-initialize any stack variables that may be passed
_