Re: [PATCH v3] riscv: stacktrace: fix stack-out-of-bounds in walk_stackframe()

From: Nam Cao <namcao@linutronix.de>
To: Jiakai Xu <xujiakai2025@iscas.ac.cn>,
	linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org
Cc: Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Chunyan Zhang <zhangchunyan@iscas.ac.cn>,
	Jiakai Xu <xujiakai2025@iscas.ac.cn>,
	Matthew Bystrin <dev.mbstr@gmail.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <pjw@kernel.org>, Rui Qi <qirui.001@bytedance.com>,
	Samuel Holland <samuel.holland@sifive.com>,
	Jiakai Xu <jiakaiPeanut@gmail.com>
Subject: Re: [PATCH v3] riscv: stacktrace: fix stack-out-of-bounds in walk_stackframe()
Date: Sat, 27 Jun 2026 13:59:10 +0200	[thread overview]
Message-ID: <87zf0g42k1.fsf@yellow.woof> (raw)
In-Reply-To: <20260625123906.211981-1-xujiakai2025@iscas.ac.cn>

Jiakai Xu <xujiakai2025@iscas.ac.cn> writes:
> +#ifdef CONFIG_IRQ_STACKS
> +DECLARE_PER_CPU(ulong *, irq_stack_ptr);
> +#endif

Instead of this, shouldn't we
  #include <asm/irq_stack.h>
?

> +	if (sp >= (unsigned long)task_stack_page(task) &&
> +	    sp < (unsigned long)task_stack_page(task) + THREAD_SIZE) {
> +		high = (unsigned long)task_pt_regs(task);
> +	} else if (IS_ENABLED(CONFIG_IRQ_STACKS)) {
> +		high = (unsigned long)this_cpu_read(irq_stack_ptr) +
> +		       IRQ_STACK_SIZE;

I suspect this fails to build if CONFIG_IRQ_STACKS=n, which would be
resolved if we do the suggested #include above.

> +	} else {
> +		high = (unsigned long)task_pt_regs(task);

We only get to this branch if the stack pointer is broken, right? If so,
I think printing a warning and returning is more appropriate.

Nam