linux-kernel - Re: [RFC PATCH v2 1/2] ARM/mm/fault: always goto bad_area when handling with page faults of kernel address

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Message-ID: <20251127145127.qUXs_UAE@linutronix.de>
Date: Thu, 27 Nov 2025 15:51:27 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Xie Yuanbin <xieyuanbin1@...wei.com>
Cc: viro@...iv.linux.org.uk, will@...nel.org, nico@...xnic.net,
	rmk+kernel@...linux.org.uk, linux@...linux.org.uk,
	david.laight@...box.com, rppt@...nel.org, vbabka@...e.cz,
	pfalcato@...e.de, brauner@...nel.org, lorenzo.stoakes@...cle.com,
	kuninori.morimoto.gx@...esas.com, tony@...mide.com, arnd@...db.de,
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	jack@...e.com, rjw@...ysocki.net, marc.zyngier@....com,
	linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
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	pangliyuan1@...wei.com, wangkefeng.wang@...wei.com
Subject: Re: [RFC PATCH v2 1/2] ARM/mm/fault: always goto bad_area when
 handling with page faults of kernel address

On 2025-11-27 22:01:08 [+0800], Xie Yuanbin wrote:
> --- a/arch/arm/mm/fault.c
> +++ b/arch/arm/mm/fault.c
> @@ -270,10 +270,15 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
>  	vm_flags_t vm_flags = VM_ACCESS_FLAGS;
>  
>  	if (kprobe_page_fault(regs, fsr))
>  		return 0;
>  
> +	if (unlikely(addr >= TASK_SIZE)) {
> +		fault = 0;
> +		code = SEGV_MAPERR;
> +		goto bad_area;
> +	}
>  
>  	/* Enable interrupts if they were enabled in the parent context. */
>  	if (interrupts_enabled(regs))
>  		local_irq_enable();

What is with the patch I sent wrong?

Sebastian