On 11/16/20 12:19 PM, Dmitry Vyukov wrote: > On Mon, Nov 16, 2020 at 1:16 PM Catalin Marinas <catalin.marinas@xxxxxxx> wrote: >> >> On Mon, Nov 16, 2020 at 12:50:00PM +0100, Marco Elver wrote: >>> On Mon, 16 Nov 2020 at 11:59, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: >>>> On Thu, Oct 29, 2020 at 8:57 PM 'Andrey Konovalov' via kasan-dev >>>> <kasan-dev@xxxxxxxxxxxxxxxx> wrote: >>>>> On Tue, Oct 27, 2020 at 1:44 PM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: >>>>>> >>>>>> On Thu, Oct 22, 2020 at 3:19 PM Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote: >>>>>>> >>>>>>> There's a config option CONFIG_KASAN_STACK that has to be enabled for >>>>>>> KASAN to use stack instrumentation and perform validity checks for >>>>>>> stack variables. >>>>>>> >>>>>>> There's no need to unpoison stack when CONFIG_KASAN_STACK is not enabled. >>>>>>> Only call kasan_unpoison_task_stack[_below]() when CONFIG_KASAN_STACK is >>>>>>> enabled. >>>>>>> >>>>>>> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> >>>>>>> Link: https://linux-review.googlesource.com/id/If8a891e9fe01ea543e00b576852685afec0887e3 >>>>>>> --- >>>>>>> arch/arm64/kernel/sleep.S | 2 +- >>>>>>> arch/x86/kernel/acpi/wakeup_64.S | 2 +- >>>>>>> include/linux/kasan.h | 10 ++++++---- >>>>>>> mm/kasan/common.c | 2 ++ >>>>>>> 4 files changed, 10 insertions(+), 6 deletions(-) >>>>>>> >>>>>>> diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S >>>>>>> index ba40d57757d6..bdadfa56b40e 100644 >>>>>>> --- a/arch/arm64/kernel/sleep.S >>>>>>> +++ b/arch/arm64/kernel/sleep.S >>>>>>> @@ -133,7 +133,7 @@ SYM_FUNC_START(_cpu_resume) >>>>>>> */ >>>>>>> bl cpu_do_resume >>>>>>> >>>>>>> -#ifdef CONFIG_KASAN >>>>>>> +#if defined(CONFIG_KASAN) && 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 c8daa92f38dc..5d3a0b8fd379 100644 >>>>>>> --- a/arch/x86/kernel/acpi/wakeup_64.S >>>>>>> +++ b/arch/x86/kernel/acpi/wakeup_64.S >>>>>>> @@ -112,7 +112,7 @@ SYM_FUNC_START(do_suspend_lowlevel) >>>>>>> movq pt_regs_r14(%rax), %r14 >>>>>>> movq pt_regs_r15(%rax), %r15 >>>>>>> >>>>>>> -#ifdef CONFIG_KASAN >>>>>>> +#if defined(CONFIG_KASAN) && 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 3f3f541e5d5f..7be9fb9146ac 100644 >>>>>>> --- a/include/linux/kasan.h >>>>>>> +++ b/include/linux/kasan.h >>>>>>> @@ -68,8 +68,6 @@ static inline void kasan_disable_current(void) {} >>>>>>> >>>>>>> void kasan_unpoison_memory(const void *address, size_t size); >>>>>>> >>>>>>> -void kasan_unpoison_task_stack(struct task_struct *task); >>>>>>> - >>>>>>> void kasan_alloc_pages(struct page *page, unsigned int order); >>>>>>> void kasan_free_pages(struct page *page, unsigned int order); >>>>>>> >>>>>>> @@ -114,8 +112,6 @@ void kasan_restore_multi_shot(bool enabled); >>>>>>> >>>>>>> static inline void kasan_unpoison_memory(const void *address, size_t size) {} >>>>>>> >>>>>>> -static inline void kasan_unpoison_task_stack(struct task_struct *task) {} >>>>>>> - >>>>>>> static inline void kasan_alloc_pages(struct page *page, unsigned int order) {} >>>>>>> static inline void kasan_free_pages(struct page *page, unsigned int order) {} >>>>>>> >>>>>>> @@ -167,6 +163,12 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; } >>>>>>> >>>>>>> #endif /* CONFIG_KASAN */ >>>>>>> >>>>>>> +#if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK >>>>>> >>>>>> && defined(CONFIG_KASAN_STACK) for consistency >>>>> >>>>> CONFIG_KASAN_STACK is different from other KASAN configs. It's always >>>>> defined, and its value is what controls whether stack instrumentation >>>>> is enabled. >>>> >>>> Not sure why we did this instead of the following, but okay. >>>> >>>> config KASAN_STACK >>>> - int >>>> - default 1 if KASAN_STACK_ENABLE || CC_IS_GCC >>>> - default 0 >>>> + bool >>>> + default y if KASAN_STACK_ENABLE || CC_IS_GCC >>>> + default n >>> >>> I wondered the same, but then looking at scripts/Makefile.kasan I >>> think it's because we directly pass it to the compiler: >>> ... >>> $(call cc-param,asan-stack=$(CONFIG_KASAN_STACK)) \ >>> ... >> >> Try this instead: >> >> $(call cc-param,asan-stack=$(if $(CONFIG_KASAN_STACK),1,0)) \ > > > We could have just 1 config instead of 2 as well. > For gcc we could do no prompt and default value y, and for clang -- > prompt and default value n. I think it should do what we need. > I agree with Catalin's proposal since it should simplify things. Nit: 'default n' is the default hence I do not think it should be required explicitly. -- Regards, Vincenzo
