:Hi there,
:
:First of all: I want to apologise for my poor english.
:
:Today me and a few friends of mine discussed the shells' (well, shell is
:actualy one of: sh/bash/csh/tcsh... not tested for ksh) command line expansion
:routines, mainly because of a problem discovered by one of my friends. I'm not
:sure if this is something new... So, let me explain what he found. It seems
:that the shell wants to allocate enough memory to hold the entire command line
:when expanding all of the arguments and we can force it to allocate hudge
:ammount of memory with a tricky command like this:
:
:carnivoro# /bin/csh -c `cat /dev/urandom`
You can trivially write any program to allocate memory continuously.
This isn't really a security problem with shells. If you want to cap
memory useage you can set a datasize limit. It doesn't cap everything
(i.e. it doesn't cap mmap() use), but it does cover the most common
mistakes that users make.
-Matt
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