Buffer
Overflow Intro. ©2002, Jedidiah R. Crandall, Susan L. Gerhart, Jan G.
Hogle.
http://sfsecurity.pr.erau.edu
Executing
subroutines requires stacks to keep track of returns
A stack is like a stack of trays in a
cafeteria. You can only put one on
the top or take one off the top. You cant touch any in the middle or on
the bottom.
If
Norman is executing subroutine R and the instruction at mailbox number 37 tells him to call subroutine S at mailbox 82, he
writes 37 on a tray and puts (or pushes) it on
the stack. This tray is called a return pointer. Then he can jump to mailbox 82.
Then
the instruction in mailbox 83 tells him to call subroutine T at mailbox 112 so he writes 83 on a tray and puts (pushes) it on a
stack.
When
subroutine T is finished he grabs the tray off top of the stack (or pops it), sees the 83 written on it, and knows where to resume
(84).
When
S is finished he pops another tray, sees the 37, and can resume where he left off with R (at 38).