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Re: /dev/fb* permissions, local DoS



On Sun, Nov 19, 2000 at 07:31:36PM +0100, Michael Schmitz wrote:
> > 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).
> 
> Should not happen - can you post a panic message? 

on a sidenote is there any other way of capturing panic messages then
echo 10000 > /proc/sys/kernel/panic and writing the damn thing down?
(it was not logged) 

NIP: C0010F18 XER: 00000000 LR: C0133B94 REGS: c162bd40 TRAP: 0600
MSR: 00009032 [EEIRDRME]
TASK = c162a000[485] 'cat' mm->pgd c1627000 Last syscall: 4
last math c162a000
GPR00: 00000080 C162BDF0 C162A000 CC003000 01843A9C 00000000 CC002FFC 00000008
GPR08: 01000000 C1857160 00000000 00000004 00000020 0184AFDC 00000000 00000000
GPR16: 00000001 7FFFFA44 7FFFF920 00000002 00009032 0162BE80 00000000 C0003B9C
GPR16: C00038D0 00000000 01843AA0 C3837358 C018853C 00000000 C1857000 00001000
Call backtrace:
C0133B10 C002EF94 C0003924 017E06B0 01800B70 01801630 0170C75C
00000000
Kernel panic: Exception in kernel pc c0010f18 signal 7


these are the only symbols found in /boot/System.map-2.2.17:

C0003B9C: c0003b9c T int_return
	  c0003b9c T ret_from_syscall
C00038D0: c00038d0 t DoSyscall
C018853C: c018853c d aty128fb_ops
C0003924: c0003924 T syscall_ret_1

-- 
Ethan Benson
http://www.alaska.net/~erbenson/

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