linux-hardening - Re: [PATCH] PM: hibernate: Fix level3 translation fault in swsusp

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Message-ID: <ZeBRfxQ8WTEVzpfL@kernel.org>
Date: Thu, 29 Feb 2024 11:42:23 +0200
From: Mike Rapoport <rppt@...nel.org>
To: Yaxiong Tian <13327272236@....com>
Cc: David Hildenbrand <david@...hat.com>, rafael@...nel.org, pavel@....cz,
	len.brown@...el.com, keescook@...omium.org, tony.luck@...el.com,
	gpiccoli@...lia.com, akpm@...ux-foundation.org, ardb@...nel.org,
	wangkefeng.wang@...wei.com, catalin.marinas@....com,
	will@...nel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
	Yaxiong Tian <tianyaxiong@...inos.cn>,
	xiongxin <xiongxin@...inos.cn>
Subject: Re: [PATCH] PM: hibernate: Fix level3 translation fault in
 swsusp_save()

On Tue, Feb 27, 2024 at 03:51:25PM +0800, Yaxiong Tian wrote:
> 
> 在 2024/2/26 17:14, Mike Rapoport 写道:
> > On Mon, Feb 26, 2024 at 09:37:06AM +0100, David Hildenbrand wrote:
> > > On 26.02.24 04:42, Yaxiong Tian wrote:
> > > > From: Yaxiong Tian <tianyaxiong@...inos.cn>
> > > > 
> > > > On ARM64 machines using UEFI, if the linear map is not set (can_set_direct_map()
> > > > return false), swsusp_save() will fail due to can't finding the map table
> > > > under the nomap memory.such as:
> > can_set_direct_map() has nothing to do with presence or absence of the
> > linear map.
> > 
> > Do you mean that kernel_page_present() presumes that a page is present when
> > can_set_direct_map() returns false even for NOMAP ranges?
> Yes， in swsusp_save()->copy_data_pages()->page_is_saveable(),
> kernel_page_present() presumes that a page is present when
> can_set_direct_map()
> returns false even for NOMAP ranges.So NOMAP pages will saved in after,and
> then
> cause level3 translation fault in this pages.

So this should be the description of the problem in the changelog rather
than saying "if the linear map is not set (can_set_direct_map() return
false)"

> > > > QEMU ARM64 using UEFI also has the problem by setting can_set_direct_map()
> > > > return false.
> >
> > Huh?
> > Why would you do that?
> >
> I discovered this problem when upgrading from 5.4 to 6.6 using the 5.4
> configuration.
> So I using latest linux-next code,find the problem still exist.To rule out
> the effects
> of a particular machine，I also use qemu to check it.

I believe this can be reproduced if you boot with rodata=off and then
a better description would be something like

	This issue can be reproduced in QEMU when booting with rodata=off

-- 
Sincerely yours,
Mike.