COMMAND

    Symmetric Multiprocessing (SMP)

SYSTEMS AFFECTED

    BSDi 4.0.1

PROBLEM

    Ben Lull  found following.   A vulnerbility  exists in  BSDi 4.0.1
    Symmetric  Multiprocessing  (SMP).   During  high  CPU usage it is
    possible to cause BSDi  4.0.1 (possibly others but  untested) with
    all current patches to stop  responding and 'lock up' when  a call
    to fstat is made.  This  is very simple to reproduce.   Simply run
    a few  instances of  commands which  will eat  up large amounts of
    CPU (top -s .1).  When the CPU hits a reasonable amount, begin  to
    run fstat.  After the  first 20-30 lines your machine  should stop
    responding.

SOLUTION

    At this time, after consulting  BSDi, it has been determined  that
    this issue  has yet  to be  encountered.   The following temporary
    fixes should be able to prevent  this in the future until BSDi  is
    able to release an official patch:

        1.) Simply chmod 000 to /usr/bin/fstat
        2.) Either  move or  remove /etc/mp.config.   During boot,  if
            this file is not found, BSDi will not boot into SMP mode.

    FreeBSD 3.2 SMP seems to be fine.  The machine used to test it  is
    a dual P-III with ASUS motherboard.