From: devzero@web.de
To: linux-kernel@vger.kernel.org
Subject: System reboot triggered by just reading a device file....!?
Date: Wed, 21 Nov 2007 00:06:57 +0100 [thread overview]
Message-ID: <2097505946@web.de> (raw)
good evening,
i stumbled over some funny issue when trying windirstat (like KDirStat) with wine.
after running that tool for a while my system rebooted. i could reproduce this with every run.
after some deep investigation (i thought i had stability issues with my system and spent more than an hour on this) i found out, that the reboot is being triggered by iTCO_wdt ( /dev/watchdog )
this is how to reproduce:
- be root
- cat /dev/watchdog or dd if=/dev/watchdog of=/dev/zero bs=1 count=1 or .....
- wait one minute........
*reboot*!
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.
ok - when i`m root , i shouldn`t do stupid things and be careful, but i thought reading/crawling trough a filesystem (r/o, btw.) with some tool which is built to do exactly this wasn`t so stupid - even from within wine.
think of an admin writing a quick&dirty script for intrusion detection (find / -exec md5sum {} \; >/tmp/need-no-tripwire) and forgetting to exclude /dev, /sys or /proc appropriately......
think of someone exporting "/" via samba (readonly) and then navigating trough the /dev directory....
stupid?
i don`t think so.....i have seen worse things...... :)
should someone get punished by an accidental system reboot and should he need to spend his time on this to investigate why this happens?
i`d wish there would be some fence around this or iTCO_wdt /dev/watchdog not being active after a default desktop installation.
i`d be interested if i`m the only one who thinks this is strange/dangerous behaviour.
regards
roland
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next reply other threads:[~2007-11-20 23:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-20 23:06 devzero [this message]
2007-11-20 23:51 ` System reboot triggered by just reading a device file....!? Matt Mackall
[not found] <fa.NKMd2cOUI5zSAFh0xiVy3hZdy3s@ifi.uio.no>
2007-11-20 23:34 ` Robert Hancock
-- strict thread matches above, loose matches on Subject: below --
2007-11-21 0:01 devzero
2007-11-21 12:29 ` Simon Arlott
2007-11-22 19:54 devzero
2007-11-22 20:42 ` Clemens Koller
2007-11-22 21:22 devzero
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