Messages in this thread | | | Date | Fri, 26 Mar 1999 17:52:02 +0100 | From | Pavel Machek <> | Subject | Re: total freeze with framebuffer + X |
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Hi!
> Considering that most distributions install X so that anybody can start it, even > if he's not at the console, it might be considered a security issue. Currently I > put a wrapper around startx so only I can start it.
People around XFree tell you to _never_ allow people running startx. xdm is preffered method... (Well, I still use startx ;-).
> > Try to shutdown a machine from within X - this will hang your machine too. > > This is not a kernel bug, neither it is X. It is just doing stupid things > > (as root, and X "is" root-privileged) in UNIX causes problems. It is fine > > by me ;) > > why is shutting down a machine from within X stupid? I don't understand this. > If I have sysvinit, and my default runlevel is 5, then I would expect to be > able to shut down my system by typing /sbin/shutdown or whatever in an xterm.
Just guessing, but it is generally bad idea to hit X with kill -9. When you shutdown and X are running, that _might_ happen. I do not know consequences - trashed display is the obvious one.
Pavel PS: Really, X is not normal app. It has root privileges and direct access to hardware. You better be carefull.
PPS: Do you want to crash machine? Nearly any machine running linux+X... Start few processess, get few MB into swap. Now start switching to/from X windows. This works on 2.1.70 sparclinuxes in school, linux 2.0.30 + X with s3 in school, it used to work on my old 486 with tvga8900... You can get it to unusable console (tvga8900, sparc) or even complete system freeze (s3).
Linux console has design problems (KDSETMODE is working on _current_ console. but what if someone changes console in between? how do you get new console? OPENQUERY + ACTIVATE. Aha, but there's race between those two.)
I'd clean that up... But I'm afraid linus will just kill such interface change...
Pavel
-- I'm really pavel@atrey.karlin.mff.cuni.cz. Pavel Look at http://atrey.karlin.mff.cuni.cz/~pavel/ ;-).
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