linux-kernel - Re: [PATCH -next] x86: Prevent KASAN false positive warnings in __show

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Message-ID: <r3gkmgetikfsuggva42qnfxzx3pdiy3vtl25fepfvvacvrzyjz@xmgcvxuquary>
Date: Thu, 28 Aug 2025 12:16:17 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Tengda Wu <wutengda@...weicloud.com>
Cc: Andrey Ryabinin <ryabinin.a.a@...il.com>, x86@...nel.org, 
	Thomas Gleixner <tglx@...utronix.de>, Alexander Potapenko <glider@...gle.com>, 
	Andrey Konovalov <andreyknvl@...il.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, Dmitry Vyukov <dvyukov@...gle.com>, 
	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org, 
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH -next] x86: Prevent KASAN false positive warnings in
 __show_regs()

On Thu, Aug 28, 2025 at 08:06:17PM +0800, Tengda Wu wrote:
> +++ b/arch/x86/kernel/dumpstack.c
> @@ -189,9 +189,15 @@ static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
>         unsigned long visit_mask = 0;
>         int graph_idx = 0;
>         bool partial = false;
> +       bool kasan_disabled = false;
>  
>         printk("%sCall Trace:\n", log_lvl);
>  
> +       if (task != current) {
> +               kasan_disable_current();
> +               kasan_disabled = true;
> +       }

Looks reasonable to me, though note that some callers pass a NULL @task
to indicate 'current'.

(No idea why, that subtlety should probably be removed...)

So this might need to be

	if (task && task != current) {
		...

-- 
Josh