Re: [PATCH] Fix mmap_kmem (was: [question] What's the differencebetween /dev/kmem and /dev/mem)

[Steven Rostedt]

On Wed, 2005-08-17 at 00:33 +0100, Alan Cox wrote:
> 
> If you use /dev/mem you should know what you are doing. Even with
> "checks" dd if=/dev/zero of=/dev/mem will do bad things. Trapping
> obviously bad cases is fine, but complete sanity checking may actually
> be counter productive.
> 

Sometimes "dd if=/dev/zero of=/dev/mem" is helpful. When I was in Spain
for some time, I needed to transfer lots of pictures to my home machine.
But all I had access to was a broken Windows box that I could ssh but
not scp?  So I (stupidly) started a ftp daemon and started transfering
them that way. I thought that creating a temp account and then changing
the password via ssh would work.  

Well, the next day I was completely rooted (thank god it was only a box
in my DMZ). Still, I was thousands of miles away and needed to kill the
box. If I can't use it, I certainly wont let someone else use it.  They
took over pretty much all control to shutdown the machine remotely.  So
I finally was able to do the duty with "dd if=/dev/zero of=/dev/mem".  

And that's my story where that can be your friend :-)

-- Steve


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