linux-kernel - Re: [PATCH] memory:bugxfix panic on cat or write /dev/kmem

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Message-ID: <20160627113757.GH31799@dhcp22.suse.cz>
Date:	Mon, 27 Jun 2016 13:37:57 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	"Chenjie (K)" <chenjie6@...wei.com>
Cc:	linux-mm@...ck.org, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, David.Woodhouse@...el.com,
	zhihui.gao@...wei.com, panxuesong@...wei.com
Subject: Re: [PATCH] memory:bugxfix panic on cat or write /dev/kmem

On Sat 25-06-16 09:20:06, Chenjie (K) wrote:
> 
> 
> On 2016/6/23 20:42, Michal Hocko wrote:
> > On Fri 24-06-16 01:30:10, chenjie6@...wei.com wrote:
> > > From: chenjie <chenjie6@...wei.com>
> > > 
> > > cat /dev/kmem and echo > /dev/kmem will lead panic
> > 
> > Writing to /dev/kmem without being extremely careful is a disaster AFAIK
> > and even reading from the file can lead to unexpected results. Anyway
> > I am trying to understand what exactly you are trying to fix here. Why
> > writing to/reading from zero pfn should be any special wrt. any other
> > potentially dangerous addresses
> > 
> 
> cat /dev/mem not panic. cat /dev/kmem, just the user's operation for
> nothing.

I am sorry, but I do not follow. Could you be more specific please?
-- 
Michal Hocko
SUSE Labs