* Andrey Ryabinin <aryabi...@virtuozzo.com> wrote:
> get_wchan() is racy by design, it may access volatile stack
> of running task, thus it may access redzone in a stack frame
> and cause KASAN to warn about this.
>
> Use READ_ONCE_NOCHECK() to silence these warnings.
>
> Reported-by: Sasha Levin <sasha.le...@oracle.com>
> Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
> ---
> arch/x86/kernel/process.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
> index 39e585a..e28db18 100644
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -550,14 +550,14 @@ unsigned long get_wchan(struct task_struct *p)
> if (sp < bottom || sp > top)
> return 0;
>
> - fp = READ_ONCE(*(unsigned long *)sp);
> + fp = READ_ONCE_NOCHECK(*(unsigned long *)sp);
> do {
> if (fp < bottom || fp > top)
> return 0;
> - ip = READ_ONCE(*(unsigned long *)(fp + sizeof(unsigned long)));
> + ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned
> long)));
> if (!in_sched_functions(ip))
> return ip;
> - fp = READ_ONCE(*(unsigned long *)fp);
> + fp = READ_ONCE_NOCHECK(*(unsigned long *)fp);
> } while (count++ < 16 && p->state != TASK_RUNNING);
> return 0;
> }
Hm, exactly how is the 'red zone' defined? Is this about the current task
mostly,
or when doing get_wchan() on other tasks?
Thanks,
Ingo
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