linux-kernel - Re: [PATCH] x86: fix system die when load with "reservetop" parameter

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <4A91EB08.6030009@cn.fujitsu.com>
Date:	Mon, 24 Aug 2009 09:21:12 +0800
From:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Yinghai Lu <yinghai@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>, x86@...nel.org
Subject: Re: [PATCH] x86: fix system die when load with "reservetop"	parameter



Ingo Molnar wrote:
> * Xiao Guangrong <xiaoguangrong@...fujitsu.com> wrote:
> 
>> The system will die if the kernel is booted with "reservetop" 
>> parameter, in present code, parse "reservetop" parameter after 
>> early_ioremap_init(), and some function still use early_ioremap() 
>> after it.
> 
> btw., what are you using the 'reservetop' boot option for?
> 

Hi Ingo,

Actually, this bug is detected by my review first, then confirm it by
loading with "reservetop" parameter

>> The problem is, "reservetop" parameter can modify 'FIXADDR_TOP', 
>> then the virtual address got by early_ioremap() is base on old 
>> 'FIXADDR_TOP', but the page mapping is base on new 'FIXADDR_TOP', 
>> it will occur page fault, and the IDT is not prepare yet, so, the 
>> system is dead.
>>
>> So, put parse_early_param() in the front of early_ioremap_init() 
>> in this patch.
>>
>> Signed-off-by: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
>> ---
>>  arch/x86/kernel/setup.c |   10 +++++-----
>>  1 files changed, 5 insertions(+), 5 deletions(-)
> 
> Does this bug trigger in 2.6.30 too?
> 
> I'm quite nervous about doing this change so late in the .31 cycle, 
> we've got a hundred early parameters that now get executed much 
> earlier than before. No way can i test all of them and others 
> testing it (like in your case) takes time to trickle through.
> 
> So unless this is a .31 regression i'd be inclined to queue it up 
> for .32.
> 

OK, this parameter is introduced in v2.6.27, but It seems like less
people use it and no one report this bug before. So, I think we can
queue it up for .32

Thanks,
Xiao
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/