[PATCH v2] riscv: stacktrace: fix stack-out-of-bounds in walk_stackframe()

[Matthew Bystrin]

Hi!

> @@ -68,19 +68,24 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
>  		pc = task->thread.ra;
>  	}
>  
> +	if (!task)
> +		task = current;
> +
> +	high = (unsigned long)task_pt_regs(task);

After noticing end_of_stack() function I'm not sure task_pt_regs() is the best
candidate for the boundary. Let's see what maintainers are going to say.

> +
>  	for (;;) {
>  		struct stackframe *frame;
>  
>  		if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc))))
>  			break;
>  
> -		if (unlikely(!fp_is_valid(fp, sp)))
> +		if (unlikely(!fp_is_valid(fp, sp, high)))
>  			break;
>  
>  		/* Unwind stack frame */
>  		frame = (struct stackframe *)fp - 1;
>  		sp = fp;
> -		if (regs && (regs->epc == pc) && fp_is_valid(frame->ra, sp)) {
> +		if (regs && (regs->epc == pc) && fp_is_valid(frame->ra, sp, high)) {
>  			/* We hit function where ra is not saved on the stack */
>  			fp = frame->ra;
>  			pc = regs->ra;
> -- 
> 2.34.1

All in all looks fine.

Reviewed-by: Matthew Bystrin <dev.mbstr at gmail.com>

-- 
Best regards
Matt