[PATCH v4] kasan: remove redundant config option

[PATCH v4] kasan: remove redundant config option

[Walter Wu]

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.

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

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: Andrew Morton <akpm@linux-foundation.org>
---

v4: After this patch sent, someone had modification about KASAN_STACK,
    so I need to rebase codebase. Thank Andrey for your pointing.

---
 arch/arm64/kernel/sleep.S        |  2 +-
 arch/x86/kernel/acpi/wakeup_64.S |  2 +-
 include/linux/kasan.h            |  2 +-
 lib/Kconfig.kasan                |  8 ++------
 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(+), 16 deletions(-)

diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index 5bfd9b87f85d..4ea9392f86e0 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/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
diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
index 56b6865afb2a..d5d8a352eafa 100644
--- a/arch/x86/kernel/acpi/wakeup_64.S
+++ b/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.
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index b91732bd05d7..14f72ec96492 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -330,7 +330,7 @@ static inline bool kasan_check_byte(const void *address)
 
 #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) {}
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index 624ae1df7984..cffc2ebbf185 100644
--- a/lib/Kconfig.kasan
+++ b/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
@@ -154,11 +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
-	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
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index b5e08d4cefec..7b53291dafa1 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -63,7 +63,7 @@ void __kasan_unpoison_range(const void *address, size_t size)
 	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)
 {
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 8c55634d6edd..3436c6bf7c0c 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -231,7 +231,7 @@ void *kasan_find_first_bad_addr(void *addr, size_t size);
 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) { }
diff --git a/mm/kasan/report_generic.c b/mm/kasan/report_generic.c
index 41f374585144..de732bc341c5 100644
--- a/mm/kasan/report_generic.c
+++ b/mm/kasan/report_generic.c
@@ -128,7 +128,7 @@ void kasan_metadata_fetch_row(char *buffer, void *row)
 	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)
diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
index 1e000cc2e7b4..abf231d209b1 100644
--- a/scripts/Makefile.kasan
+++ b/scripts/Makefile.kasan
@@ -2,6 +2,12 @@
 CFLAGS_KASAN_NOSANITIZE := -fno-builtin
 KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET)
 
+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 \
-		-mllvm -hwasan-instrument-stack=$(CONFIG_KASAN_STACK) \
+		-mllvm -hwasan-instrument-stack=$(stack_enable) \
 		-mllvm -hwasan-use-short-granules=0 \
 		$(instrumentation_flags)
 
diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
index 269967c4fc1b..a56c36470cb1 100644
--- a/security/Kconfig.hardening
+++ b/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
-- 
2.18.0

Re: [PATCH v4] kasan: remove redundant config option

[Walter Wu]

On Fri, 2021-02-26 at 09:25 +0800, Walter Wu wrote:
> 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.
> 
> [1]: https://bugzilla.kernel.org/show_bug.cgi?id=210221
> 
> 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: Andrew Morton <akpm@linux-foundation.org>
> ---
> 
> v4: After this patch sent, someone had modification about KASAN_STACK,
>     so I need to rebase codebase. Thank Andrey for your pointing.
> 
Hi Andrew,

Could you pick this v4 patch up into mm?
Thanks.

Walter

> ---
>  arch/arm64/kernel/sleep.S        |  2 +-
>  arch/x86/kernel/acpi/wakeup_64.S |  2 +-
>  include/linux/kasan.h            |  2 +-
>  lib/Kconfig.kasan                |  8 ++------
>  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(+), 16 deletions(-)
> 
> diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
> index 5bfd9b87f85d..4ea9392f86e0 100644
> --- a/arch/arm64/kernel/sleep.S
> +++ b/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
> diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
> index 56b6865afb2a..d5d8a352eafa 100644
> --- a/arch/x86/kernel/acpi/wakeup_64.S
> +++ b/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.
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index b91732bd05d7..14f72ec96492 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -330,7 +330,7 @@ static inline bool kasan_check_byte(const void *address)
>  
>  #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) {}
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> index 624ae1df7984..cffc2ebbf185 100644
> --- a/lib/Kconfig.kasan
> +++ b/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
> @@ -154,11 +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
> -	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
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index b5e08d4cefec..7b53291dafa1 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -63,7 +63,7 @@ void __kasan_unpoison_range(const void *address, size_t size)
>  	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)
>  {
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 8c55634d6edd..3436c6bf7c0c 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -231,7 +231,7 @@ void *kasan_find_first_bad_addr(void *addr, size_t size);
>  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) { }
> diff --git a/mm/kasan/report_generic.c b/mm/kasan/report_generic.c
> index 41f374585144..de732bc341c5 100644
> --- a/mm/kasan/report_generic.c
> +++ b/mm/kasan/report_generic.c
> @@ -128,7 +128,7 @@ void kasan_metadata_fetch_row(char *buffer, void *row)
>  	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)
> diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
> index 1e000cc2e7b4..abf231d209b1 100644
> --- a/scripts/Makefile.kasan
> +++ b/scripts/Makefile.kasan
> @@ -2,6 +2,12 @@
>  CFLAGS_KASAN_NOSANITIZE := -fno-builtin
>  KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET)
>  
> +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)) \
>  	 $(call cc-param,asan-instrument-allocas=1)
>  endif
>  
> @@ -42,7 +48,7 @@ else
>  endif
>  
>  CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
> -		-mllvm -hwasan-instrument-stack=$(CONFIG_KASAN_STACK) \
> +		-mllvm -hwasan-instrument-stack=$(stack_enable) \
>  		-mllvm -hwasan-use-short-granules=0 \
>  		$(instrumentation_flags)
>  
> diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
> index 269967c4fc1b..a56c36470cb1 100644
> --- a/security/Kconfig.hardening
> +++ b/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

Re: [PATCH v4] kasan: remove redundant config option

[Walter Wu]

On Wed, 2021-03-03 at 19:48 +0800, Walter Wu wrote:
> On Fri, 2021-02-26 at 09:25 +0800, Walter Wu wrote:
> > 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.
> > 
> > [1]: https://bugzilla.kernel.org/show_bug.cgi?id=210221
> > 
> > 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: Andrew Morton <akpm@linux-foundation.org>
> > ---
> > 
> > v4: After this patch sent, someone had modification about KASAN_STACK,
> >     so I need to rebase codebase. Thank Andrey for your pointing.
> > 
> Hi Andrew,
> 
> Could you pick this v4 patch up into mm?
> Thanks.
> 
> Walter
> 
> > ---
> >  arch/arm64/kernel/sleep.S        |  2 +-
> >  arch/x86/kernel/acpi/wakeup_64.S |  2 +-
> >  include/linux/kasan.h            |  2 +-
> >  lib/Kconfig.kasan                |  8 ++------
> >  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(+), 16 deletions(-)
> > 
> > diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
> > index 5bfd9b87f85d..4ea9392f86e0 100644
> > --- a/arch/arm64/kernel/sleep.S
> > +++ b/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
> > diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
> > index 56b6865afb2a..d5d8a352eafa 100644
> > --- a/arch/x86/kernel/acpi/wakeup_64.S
> > +++ b/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.
> > diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> > index b91732bd05d7..14f72ec96492 100644
> > --- a/include/linux/kasan.h
> > +++ b/include/linux/kasan.h
> > @@ -330,7 +330,7 @@ static inline bool kasan_check_byte(const void *address)
> >  
> >  #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) {}
> > diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> > index 624ae1df7984..cffc2ebbf185 100644
> > --- a/lib/Kconfig.kasan
> > +++ b/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
> > @@ -154,11 +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
> > -	default 1 if KASAN_STACK_ENABLE || CC_IS_GCC
> > -	default 0
> > -

Hi Andrew,

I see my v4 patch is different in the next tree now. please see below
information.
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=ebced5fb0ef969620ecdc4011f600f9e7c229a3c
The different is in lib/Kconfig.kasan.
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/diff/lib/Kconfig.kasan?id=ebced5fb0ef969620ecdc4011f600f9e7c229a3c

Would you please help to check it.
Thanks.

Walter

> >  config KASAN_SW_TAGS_IDENTIFY
> >  	bool "Enable memory corruption identification"
> >  	depends on KASAN_SW_TAGS
> > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > index b5e08d4cefec..7b53291dafa1 100644
> > --- a/mm/kasan/common.c
> > +++ b/mm/kasan/common.c
> > @@ -63,7 +63,7 @@ void __kasan_unpoison_range(const void *address, size_t size)
> >  	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)
> >  {
> > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> > index 8c55634d6edd..3436c6bf7c0c 100644
> > --- a/mm/kasan/kasan.h
> > +++ b/mm/kasan/kasan.h
> > @@ -231,7 +231,7 @@ void *kasan_find_first_bad_addr(void *addr, size_t size);
> >  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) { }
> > diff --git a/mm/kasan/report_generic.c b/mm/kasan/report_generic.c
> > index 41f374585144..de732bc341c5 100644
> > --- a/mm/kasan/report_generic.c
> > +++ b/mm/kasan/report_generic.c
> > @@ -128,7 +128,7 @@ void kasan_metadata_fetch_row(char *buffer, void *row)
> >  	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)
> > diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
> > index 1e000cc2e7b4..abf231d209b1 100644
> > --- a/scripts/Makefile.kasan
> > +++ b/scripts/Makefile.kasan
> > @@ -2,6 +2,12 @@
> >  CFLAGS_KASAN_NOSANITIZE := -fno-builtin
> >  KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET)
> >  
> > +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)) \
> >  	 $(call cc-param,asan-instrument-allocas=1)
> >  endif
> >  
> > @@ -42,7 +48,7 @@ else
> >  endif
> >  
> >  CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
> > -		-mllvm -hwasan-instrument-stack=$(CONFIG_KASAN_STACK) \
> > +		-mllvm -hwasan-instrument-stack=$(stack_enable) \
> >  		-mllvm -hwasan-use-short-granules=0 \
> >  		$(instrumentation_flags)
> >  
> > diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
> > index 269967c4fc1b..a56c36470cb1 100644
> > --- a/security/Kconfig.hardening
> > +++ b/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
> 

Re: [PATCH v4] kasan: remove redundant config option

[Andrew Morton]

On Thu, 11 Mar 2021 09:32:45 +0800 Walter Wu <walter-zh.wu@mediatek.com> wrote:

> 
> Hi Andrew,
> 
> I see my v4 patch is different in the next tree now. please see below
> information.
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=ebced5fb0ef969620ecdc4011f600f9e7c229a3c
> The different is in lib/Kconfig.kasan.
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/diff/lib/Kconfig.kasan?id=ebced5fb0ef969620ecdc4011f600f9e7c229a3c
> 

They look the same to me.  I did have `int' for KASAN_STACK due to a
merging mess, but I changed that to bool quite quickly.

Re: [PATCH v4] kasan: remove redundant config option

[Andrey Konovalov]

On Thu, Mar 11, 2021 at 6:45 AM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Thu, 11 Mar 2021 09:32:45 +0800 Walter Wu <walter-zh.wu@mediatek.com> wrote:
>
> >
> > Hi Andrew,
> >
> > I see my v4 patch is different in the next tree now. please see below
> > information.
> > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=ebced5fb0ef969620ecdc4011f600f9e7c229a3c
> > The different is in lib/Kconfig.kasan.
> > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/diff/lib/Kconfig.kasan?id=ebced5fb0ef969620ecdc4011f600f9e7c229a3c
> >
>
> They look the same to me.  I did have `int' for KASAN_STACK due to a
> merging mess, but I changed that to bool quite quickly.

There's still something wrong with this patch in the mm tree. The
KASAN_STACK option is duplicated in lib/Kconfig.kasan. Badly resolved
conflict with "kasan: fix KASAN_STACK dependency for HW_TAGS"?

Re: [PATCH v4] kasan: remove redundant config option

[Andrey Konovalov]

On Fri, Feb 26, 2021 at 2:25 AM Walter Wu <walter-zh.wu@mediatek.com> wrote:
>
> 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.
>
> [1]: https://bugzilla.kernel.org/show_bug.cgi?id=210221
>
> 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: Andrew Morton <akpm@linux-foundation.org>
> ---
>
> v4: After this patch sent, someone had modification about KASAN_STACK,
>     so I need to rebase codebase. Thank Andrey for your pointing.
>
> ---
>  arch/arm64/kernel/sleep.S        |  2 +-
>  arch/x86/kernel/acpi/wakeup_64.S |  2 +-
>  include/linux/kasan.h            |  2 +-
>  lib/Kconfig.kasan                |  8 ++------
>  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(+), 16 deletions(-)
>
> diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
> index 5bfd9b87f85d..4ea9392f86e0 100644
> --- a/arch/arm64/kernel/sleep.S
> +++ b/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
> diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
> index 56b6865afb2a..d5d8a352eafa 100644
> --- a/arch/x86/kernel/acpi/wakeup_64.S
> +++ b/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.
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index b91732bd05d7..14f72ec96492 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -330,7 +330,7 @@ static inline bool kasan_check_byte(const void *address)
>
>  #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) {}
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> index 624ae1df7984..cffc2ebbf185 100644
> --- a/lib/Kconfig.kasan
> +++ b/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
> @@ -154,11 +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
> -       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
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index b5e08d4cefec..7b53291dafa1 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -63,7 +63,7 @@ void __kasan_unpoison_range(const void *address, size_t size)
>         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)
>  {
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 8c55634d6edd..3436c6bf7c0c 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -231,7 +231,7 @@ void *kasan_find_first_bad_addr(void *addr, size_t size);
>  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) { }
> diff --git a/mm/kasan/report_generic.c b/mm/kasan/report_generic.c
> index 41f374585144..de732bc341c5 100644
> --- a/mm/kasan/report_generic.c
> +++ b/mm/kasan/report_generic.c
> @@ -128,7 +128,7 @@ void kasan_metadata_fetch_row(char *buffer, void *row)
>         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)
> diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
> index 1e000cc2e7b4..abf231d209b1 100644
> --- a/scripts/Makefile.kasan
> +++ b/scripts/Makefile.kasan
> @@ -2,6 +2,12 @@
>  CFLAGS_KASAN_NOSANITIZE := -fno-builtin
>  KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET)
>
> +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)) \
>          $(call cc-param,asan-instrument-allocas=1)
>  endif
>
> @@ -42,7 +48,7 @@ else
>  endif
>
>  CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
> -               -mllvm -hwasan-instrument-stack=$(CONFIG_KASAN_STACK) \
> +               -mllvm -hwasan-instrument-stack=$(stack_enable) \
>                 -mllvm -hwasan-use-short-granules=0 \
>                 $(instrumentation_flags)
>
> diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
> index 269967c4fc1b..a56c36470cb1 100644
> --- a/security/Kconfig.hardening
> +++ b/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
> --
> 2.18.0
>
> --
> You received this message because you are subscribed to the Google Groups "kasan-dev" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20210226012531.29231-1-walter-zh.wu%40mediatek.com.

Hi Andrew,

Looks like my patch "kasan: fix KASAN_STACK dependency for HW_TAGS"
that was merged into 5.12-rc causes a build time warning:

include/linux/kasan.h:333:30: warning: 'CONFIG_KASAN_STACK' is not
defined, evaluates to 0 [-Wundef]
#if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK

The fix for it would either be reverting the patch (which would leave
the initial issue unfixed) or applying this "kasan: remove redundant
config option" patch.

Would it be possible to send this patch (with the fix-up you have in
mm) for the next 5.12-rc?

Here are the required tags:

Fixes: d9b571c885a8 ("kasan: fix KASAN_STACK dependency for HW_TAGS")
Cc: stable@vger.kernel.org

Thanks!

Re: [PATCH v4] kasan: remove redundant config option

[Andrew Morton]

On Mon, 29 Mar 2021 16:54:26 +0200 Andrey Konovalov <andreyknvl@google.com> wrote:

> Looks like my patch "kasan: fix KASAN_STACK dependency for HW_TAGS"
> that was merged into 5.12-rc causes a build time warning:
> 
> include/linux/kasan.h:333:30: warning: 'CONFIG_KASAN_STACK' is not
> defined, evaluates to 0 [-Wundef]
> #if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
> 
> The fix for it would either be reverting the patch (which would leave
> the initial issue unfixed) or applying this "kasan: remove redundant
> config option" patch.
> 
> Would it be possible to send this patch (with the fix-up you have in
> mm) for the next 5.12-rc?
> 
> Here are the required tags:
> 
> Fixes: d9b571c885a8 ("kasan: fix KASAN_STACK dependency for HW_TAGS")
> Cc: stable@vger.kernel.org

Got it, thanks.  I updated the changelog to mention the warning fix and
moved these ahead for a -rc merge.

Re: [PATCH v4] kasan: remove redundant config option

[Catalin Marinas]

Hi Andrew,

On Tue, Mar 30, 2021 at 10:36:37PM -0700, Andrew Morton wrote:
> On Mon, 29 Mar 2021 16:54:26 +0200 Andrey Konovalov <andreyknvl@google.com> wrote:
> > Looks like my patch "kasan: fix KASAN_STACK dependency for HW_TAGS"
> > that was merged into 5.12-rc causes a build time warning:
> > 
> > include/linux/kasan.h:333:30: warning: 'CONFIG_KASAN_STACK' is not
> > defined, evaluates to 0 [-Wundef]
> > #if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
> > 
> > The fix for it would either be reverting the patch (which would leave
> > the initial issue unfixed) or applying this "kasan: remove redundant
> > config option" patch.
> > 
> > Would it be possible to send this patch (with the fix-up you have in
> > mm) for the next 5.12-rc?
> > 
> > Here are the required tags:
> > 
> > Fixes: d9b571c885a8 ("kasan: fix KASAN_STACK dependency for HW_TAGS")
> > Cc: stable@vger.kernel.org
> 
> Got it, thanks.  I updated the changelog to mention the warning fix and
> moved these ahead for a -rc merge.

Is there a chance this patch makes it into 5.12? I still get the warning
with the latest Linus' tree (v5.12-rc6-408-g52e44129fba5) when enabling
KASAN_HW_TAGS.

Thanks.

-- 
Catalin

Re: [PATCH v4] kasan: remove redundant config option

[Andrew Morton]

On Sun, 11 Apr 2021 11:53:33 +0100 Catalin Marinas <catalin.marinas@arm.com> wrote:

> Hi Andrew,
> 
> On Tue, Mar 30, 2021 at 10:36:37PM -0700, Andrew Morton wrote:
> > On Mon, 29 Mar 2021 16:54:26 +0200 Andrey Konovalov <andreyknvl@google.com> wrote:
> > > Looks like my patch "kasan: fix KASAN_STACK dependency for HW_TAGS"
> > > that was merged into 5.12-rc causes a build time warning:
> > > 
> > > include/linux/kasan.h:333:30: warning: 'CONFIG_KASAN_STACK' is not
> > > defined, evaluates to 0 [-Wundef]
> > > #if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
> > > 
> > > The fix for it would either be reverting the patch (which would leave
> > > the initial issue unfixed) or applying this "kasan: remove redundant
> > > config option" patch.
> > > 
> > > Would it be possible to send this patch (with the fix-up you have in
> > > mm) for the next 5.12-rc?
> > > 
> > > Here are the required tags:
> > > 
> > > Fixes: d9b571c885a8 ("kasan: fix KASAN_STACK dependency for HW_TAGS")
> > > Cc: stable@vger.kernel.org
> > 
> > Got it, thanks.  I updated the changelog to mention the warning fix and
> > moved these ahead for a -rc merge.
> 
> Is there a chance this patch makes it into 5.12? I still get the warning
> with the latest Linus' tree (v5.12-rc6-408-g52e44129fba5) when enabling
> KASAN_HW_TAGS.

Trying.   We're still awaiting a tested fix for
https://lkml.kernel.org/r/CA+fCnZf1ABrQg0dsxtoZa9zM1BSbLYq_Xbu+xi9cv8WAZxdC2g@mail.gmail.com

Re: [PATCH v4] kasan: remove redundant config option

[Catalin Marinas]

On Sun, Apr 11, 2021 at 03:03:16PM -0700, Andrew Morton wrote:
> On Sun, 11 Apr 2021 11:53:33 +0100 Catalin Marinas <catalin.marinas@arm.com> wrote:
> > On Tue, Mar 30, 2021 at 10:36:37PM -0700, Andrew Morton wrote:
> > > On Mon, 29 Mar 2021 16:54:26 +0200 Andrey Konovalov <andreyknvl@google.com> wrote:
> > > > Looks like my patch "kasan: fix KASAN_STACK dependency for HW_TAGS"
> > > > that was merged into 5.12-rc causes a build time warning:
> > > > 
> > > > include/linux/kasan.h:333:30: warning: 'CONFIG_KASAN_STACK' is not
> > > > defined, evaluates to 0 [-Wundef]
> > > > #if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
> > > > 
> > > > The fix for it would either be reverting the patch (which would leave
> > > > the initial issue unfixed) or applying this "kasan: remove redundant
> > > > config option" patch.
> > > > 
> > > > Would it be possible to send this patch (with the fix-up you have in
> > > > mm) for the next 5.12-rc?
> > > > 
> > > > Here are the required tags:
> > > > 
> > > > Fixes: d9b571c885a8 ("kasan: fix KASAN_STACK dependency for HW_TAGS")
> > > > Cc: stable@vger.kernel.org
> > > 
> > > Got it, thanks.  I updated the changelog to mention the warning fix and
> > > moved these ahead for a -rc merge.
> > 
> > Is there a chance this patch makes it into 5.12? I still get the warning
> > with the latest Linus' tree (v5.12-rc6-408-g52e44129fba5) when enabling
> > KASAN_HW_TAGS.
> 
> Trying.   We're still awaiting a tested fix for
> https://lkml.kernel.org/r/CA+fCnZf1ABrQg0dsxtoZa9zM1BSbLYq_Xbu+xi9cv8WAZxdC2g@mail.gmail.com

Thanks Andrew. I didn't realise it was sent and then dropped.

However, we should decouple (or rather reorder) the two patches. There's
no functional dependency between removing the redundant config option (a
fix for an existing commit) and adding support for KASAN_SW_TAGS with
gcc-11, only a conflict in scripts/Makefile.kasan. Walter's original
patch applies on top of vanilla 5.12-rc3:

https://lkml.kernel.org/r/20210226012531.29231-1-walter-zh.wu@mediatek.com

-- 
Catalin