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Re: /dev/fb* permissions, local DoS

On Sun, Nov 19, 2000 at 06:04:01AM -0900, Ethan Benson wrote:
> does anyone know why debian has /dev/fb* with 622 permissions? 
> the reason i ask is there is a pretty nasty security problem with
> this, try the following:
> cat /dev/urandom > /dev/fb0
> on my system i get a instant kernel panic (2.2.17 from ftp.kernel.org).
> since the framebuffer devices are world writable anyone with a shell
> account can crash the system, not nice. (i have a blue G3 using
> aty128fb) 
> what is broken by setting the permissions on all the framebuffer
> devices to 0600 ?

Doesn't crash my i386 (riva tnt2, XF4) - but does put pretty colors over
the top 1/3 of the screen before cat exits with "write error: No space left on


       Knuth: premature optimization is the root of all evil.
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