Buffer Overflow Return Addresses

[<luck___ () hotmail com>]

Hi hope someone could help me with a question I have. Why do many buffer overflow sploits use the %esp before the 
program has run as the return address? If im not wrong then the idea is to return into the buffer (preferable near the 
start) but the %esp before the program is run becomes %ebp during program execution and this is after the buffer in the 
stack? Would it not be better to return to (%esp before) - (length of buffer) which should place you at the start of 
the buffer assuming buffer is the first local variable to be declared (stack grows to lower addresses) This is really 
confusing me after i thought id got my head round it. 

Thanks

S Walker

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