milo-alpha-linux-DoS.txt

`Date: Fri, 5 Feb 1999 17:39:53 -0500  
From: Dave G. <[email protected]>  
To: [email protected]  
Subject: KSR[T] #009: Non Privileged Halt  
  
KSR[T] Security Advisories  
http://www.ksrt.org  
[email protected]  
  
---  
  
KSR[T] Advisory #009  
Date: Feb. 5th 1999  
ID #: NonPrivdHALT  
  
Affected Program: MILO/Alpha Linux  
  
Operating System(s): Linux (Redhat 5.x)  
  
Summary: Any local user can cause an Alpha Linux machine to  
reboot, lock up or become unstable.  
  
Problem Description: During the beta-testing of an instruction set  
auditor, the KSR[T] team found several instructions  
that caused an Alpha Linux machine to generate an  
'Oops' or to reboot/hang. This involves the call_pal  
instruction with different immediate arguments.  
  
The PALcode currently used in the MILO that comes  
with Redhat 5.x and below has two additional  
debugging PAL calls, DBGSTOP (0xAD) and NPHALT  
(0xBF). NPHALT is a non-privileged HALT  
instruction, which brings the machine straight  
back to the console even from user space.  
  
These calls were used during the development of  
MILO and were not intended for production use.  
  
Notes: We would like to thank Richard Henderson,  
Alan Cox for their help with this advisory.  
  
Special thanks to Nikita Schmidt for the  
problem description.  
  
Patch/Fix: The copies of MILO distributed at  
ftp://genie.ucd.ie/pub/alpha/milo/milo-latest  
are not vulnerable to this attack.  
  
`