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

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Message-ID: <20071120235138.GE17536@waste.org>
Date:	Tue, 20 Nov 2007 17:51:38 -0600
From:	Matt Mackall <mpm@...enic.com>
To:	devzero@....de
Cc:	linux-kernel@...r.kernel.org
Subject: Re: System reboot triggered by just reading a device file....!?

On Wed, Nov 21, 2007 at 12:06:57AM +0100, devzero@....de wrote:
> - be root

That's your first mistake.

> -  cat /dev/watchdog or dd if=/dev/watchdog of=/dev/zero bs=1 count=1 or .....
> -  wait one minute........
> 
> *reboot*!

And that's the defined behavior of /dev/watchdog, yes. Many years too
late to change it.

> i have heard 2 opinions for now (contacted the author and also discussed on wine-devel ) that this should be expected behaviour.
> 
> being sysadmin quite a while, i cannot believe that (accidentally) reading a device file (being root or not - what does that matter) triggers a system reboot.

If /dev/watchdog can be opened by non-root, that's an installation
error.

-- 
Mathematics is the supreme nostalgia of our time.
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