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    SubjectRe: Forking shell bombs

    Hello,

    Debian 3.0 (woody) stable. Kernel 2.4.21 ...
    bash 2.05a

    $ulimit -u
    1791

    ---

    No problems here. In 1-2 secs the process dies and all is ok, i can work
    with the shell without any problem.

    Seeya


    At 16:43 08/07/2003 -0400, jhigdon wrote:
    >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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