Messages in this thread | | | Date | Tue, 08 Jul 2003 16:43:18 -0400 | From | jhigdon <> | Subject | Re: Forking shell bombs |
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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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