Re: [PATCH] trace, kasan: silence Kasan warning in check_stack

[Steven Rostedt]

On Mon,  8 Feb 2016 10:39:42 -0800
Yang Shi <yang....@linaro.org> wrote:

> 
> Signed-off-by: Yang Shi <yang....@linaro.org>
> ---
>  kernel/trace/trace_stack.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
> index 202df6c..61e5e1e 100644
> --- a/kernel/trace/trace_stack.c
> +++ b/kernel/trace/trace_stack.c
> @@ -156,7 +156,7 @@ check_stack(unsigned long ip, unsigned long *stack)
>               for (; p < top && i < stack_trace_max.nr_entries; p++) {
>                       if (stack_dump_trace[i] == ULONG_MAX)
>                               break;
> -                     if (*p == stack_dump_trace[i]) {

Can you add a comment explaining this. Something like:

        /*
         * The READ_ONCE_NOCHECK() is used to let KASAN know that
         * this is not an stack-out-of-bounds error.
         */

Thanks,

-- Steve

> +                     if ((READ_ONCE_NOCHECK(*p)) == stack_dump_trace[i]) {
>                               stack_dump_trace[x] = stack_dump_trace[i++];
>                               this_size = stack_trace_index[x++] =
>                                       (top - p) * sizeof(unsigned long);