Re: Executable memory: further programs that fail

[Gordon Messmer <yinyang eburg com>]

Tim Daly wrote:
> I react to the notion that shared libraries can be placed 
> "at random" in free space. Lisp systems, database systems,
> numeric systems (e.g. large matrix computations), all rely on
> large, contiguous blocks of storage. In fact the size of the
> problem they can handle depends on the size of contiguous 
> storage. I don't understand why fragmenting free storage
> helps security.

I'm not an assembly programmer, so someone may correct me:

buffer overflow exploits rely on the ability to call a library function 
at a predictable address.  If the libraries are loaded at random 
addresses, then buffer overflow attacks have a much more difficult time 
predicting the address of a block of code to jump to.