Re: [PATCH] arm64: disable kasan when accessing frame->fp in unwind_frame

[Shi, Yang]

On 2/8/2016 12:51 AM, Andrey Ryabinin wrote:
> On 02/06/2016 02:04 AM, Yang Shi wrote:
> >   #include <asm/irq.h>
> >   #include <asm/stacktrace.h>
> > @@ -64,7 +65,9 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
> >   		return -EINVAL;
> >
> >   	frame->sp = fp + 0x10;
> > +	kasan_disable_current();
> >   	frame->fp = *(unsigned long *)(fp);
>
> It would be better to use READ_ONCE_NOCHECK() here.
> See f7d27c35ddff7 ("x86/mm, kasan: Silence KASAN warnings in get_wchan()") which solves the same problem for x86.

Thanks for the suggestion, I'm going to try it soon.

> > +	kasan_enable_current();
> >   	frame->pc = *(unsigned long *)(fp + 8);
>
> Why you left frame->pc out of scope? This line could trigger kasan as well.

Actually, it was not reported as frequently as the first one. In my 
first a couple of boot test, it was not triggered before I came up with 
the patch. The first one is triggered every time.

It will be fixed in v2 too.

Thanks,
Yang

> >   #ifdef CONFIG_FUNCTION_GRAPH_TRACER