Re: [PATCH v2] 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>,
	Samuel Holland <samuel.holland@sifive.com>
Subject: Re: [PATCH v2] riscv: stacktrace: fix stack-out-of-bounds in walk_stackframe()
Date: Fri, 19 Jun 2026 11:51:28 +0200	[thread overview]
Message-ID: <87zf0q504f.fsf@yellow.woof> (raw)
In-Reply-To: <20260517143704.659416-1-xujiakai2025@iscas.ac.cn>

Jiakai Xu <xujiakai2025@iscas.ac.cn> writes:
> +	if (!task)
> +		task = current;
> +
> +	high = (unsigned long)task_pt_regs(task);

I am concerned when CONFIG_IRQ_STACKS=y and we are on the irq stack,
wouldn't this "high" be the wrong one?

I haven't validated it, we probably need something like

if (on_thread_stack()) {
	if (!task)
        	task = current;
	high = (unsigned long)task_pt_regs(task);
} else {
	high = per_cpu(irq_stack_ptr, smp_processor_id()) + IRQ_STACK_SIZE/sizeof(ulong);
}

Nam

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