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    SubjectRe: Forking shell bombs
    Ryan Underwood wrote:

    >Hi,
    >
    >
    >
    >>That's what per-user process limits are for. Doesn't matter if it's a
    >>shellscript or something else; any system without limits set is
    >>vulnerable.
    >>
    >>
    >
    >I agree, but it would also be nice to have a way to clean up after the
    >fact without giving up the box. My limit is set at 2047 processes
    >which, while being a lot, doesn't seem like enough to guarantee a dead
    >box. (Don't many busy systems have more than this number running at any
    >given time?)
    >
    >
    >
    >>It's a base redhat kernel, after the cannot allocate memory, my system
    >>returned to normal operation and it didnt die.
    >>Is this the type of behavior you were looking for? or am i off base?
    >>
    >>Linux sloth 2.4.20-8 #1 Thu Mar 13 17:54:28 EST 2003 i686 i686 i386
    >>GNU/Linux
    >>
    >>$ :(){ :|:&};:
    >>[1] 3071
    >>
    >>$
    >>[1]+ Done : | :
    >>
    >>$ -bash: fork: Cannot allocate memory
    >>-bash: fork: Cannot allocate memory
    >>-bash: fork: Cannot allocate memory
    >>-bash: fork: Cannot allocate memory
    >>
    >>
    >
    >Nope, on my system running stock 2.4.21, after hitting enter, wait about 2
    >seconds, and the system is frozen. Telnet connects but never gets a
    >shell. None of the SysRq process-killing combos have any effect. After
    >a few failed killalls (which eventually killed the one shell I was able
    >to get), and Alt-SysRq-S never completing the sync, I gave up and
    >Alt-SysRq-B.
    >
    >What does ulimit -u say on your system? 2047 on mine.
    >
    >
    >
    $ ulimit -u
    3072


    Have you tried this on any 2.5.x kernels? Just curious to see what it
    does, I plan on giving it a go later.


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