Samu wrote:

> 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 ?
>> 
> 
> well with fbtv or fbi there's a line like this 
> (fb = open("/dev/fb0",O_WRONLY,0))

So 0620 might be better, with /dev/fb in group video or a dedicated group.

This is on a SuSE 6.4 system BTW:

crw-rw----   1 root     video     29,   0 Mar 11  2000 /dev/fb0


Michel

-- 
Earthling Michel Dänzer (MrCooper)  \  CS student and free software enthusiast
Debian GNU/Linux (powerpc,i386) user \   member of XFree86 and the DRI project


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