xterm -C not working

Bruce Evans bde at zeta.org.au
Sun Apr 25 05:55:58 PDT 2004

On Sun, 25 Apr 2004, Randy Bush wrote:

> ...
> xtem -C seems not to get console output on the xterm,
> though, if i run in non-X, i do get console messages
> ...
> not sure this is related, but i noticed that the kernel
> config
>    options         UCONSOLE
> is no longer legal (and the handbook on kernel configuration
> forgot to remove it).

This option opened a security hole in the broken TIOCCONS ioctl.
I think xterm -C uses this ioctl.  The security hole was that
everyone was permitted to take over the console.  Now only users
who can open /dev/console for reading can take it over.  The
brokenness is that TIOCCONS causes panics.  It apparently never
worked, but it causes panics more reliably now because the bad
things that it does are detected by locking assertions.


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