linux-kernel - Re: System reboot triggered by just reading a device file....!?

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Date:	Thu, 22 Nov 2007 20:54:42 +0100
From:	devzero@....de
To:	Simon Arlott <simon@...e.lp0.eu>
Cc:	Robert Hancock <hancockr@...w.ca>, linux-kernel@...r.kernel.org
Subject: Re: System reboot triggered by just reading a device file....!?

since i have gotten more or less similar answers from here, i have talked to some more people privately.

the result is interesting:
if the person i talked to was some sysadmin or related to that (i.e. some person running servers), his opinion was very similar to mine.
if the person was a developer, he didn`t really understand why i have a problem with that. "be careful if you are root" was what i got.

one of the admins gave a good statement, which i liked very much and want to share:

"even if you are root: it`s unix philosophy, that reading is harmless!"

i never thought about that, but i think that`s exactly the point and that`s why i`m feeling uncomfortable with that.

anyway - it cost me some time to find a bug which was none  and the only mistake i did was using a tool for which i was sure did nothing more than reading. so why should i care that i was root ?

need to change my own philosophy now, because i learned that reading isn`t harmless.   ;)

regards
roland

> -----Ursprüngliche Nachricht-----
> Von: "Simon Arlott" <simon@...e.lp0.eu>
> Gesendet: 21.11.07 13:30:05
> An: devzero@....de
> CC: "Robert Hancock" <hancockr@...w.ca>, linux-kernel@...r.kernel.org
> Betreff: Re: System reboot triggered by just reading a device file....!?

> 
> On Wed, November 21, 2007 00:01, devzero@....de wrote:
> >>There is.. it's called "root privileges".
> > yes, true.
> >
> > but - regardless of being a windows app or not - what if you want to take a look on your system as a whole,
> > especially when using some tool which graphically shows how and where your diskspace is being used?  if i
> > let this run from ordinary useraccount it would get lot`s of "permission denied"  and then it`s only telling
> > half of the truth.....
> 
> Such a tool shouldn't need to open any files, whether they're device files or not. Do you expect it to open
> /dev/zero etc. too and read from an infinitely sized "file"?
> 
> >> > i`d wish there would be some fence around this or iTCO_wdt /dev/watchdog not being active after a
> >> default desktop installation.
> 
> Delete it?
> 
> -- 
> Simon Arlott
> 

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