Re: [PATCH bpf-next v2 08/14] bpf: Prevent KASAN false positive with bpf_throw

[Andrey Konovalov <andreyknvl@xxxxxxxxx>]

On Wed, Aug 9, 2023 at 1:43 PM Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx> wrote:
>

Hi Kumar,

> @@ -283,8 +283,10 @@ static inline bool kasan_check_byte(const void *address)
>
>  #if defined(CONFIG_KASAN) && defined(CONFIG_KASAN_STACK)
>  void kasan_unpoison_task_stack(struct task_struct *task);
> +asmlinkage void kasan_unpoison_task_stack_below(const void *watermark);
>  #else
>  static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
> +static inline void kasan_unpoison_task_stack_below(const void *watermark) {}
>  #endif

Please also drop the kasan_unpoison_task_stack_below declaration from
mm/kasan/kasan.h.

Also, could you please split this change into 2: one that exposes
kasan_unpoison_task_stack_below and another that changes the bpf code.
This will greatly simplify backporting KASAN changes for older
kernels.

Thank you!