Improve stack description & intro

Stack.drawio

@@ -0,0 +1 @@
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index.html

@@ -148,9 +148,13 @@ layout: false
 ## Introduction
 ]
 .right-column[
-- C is full of holes, let's get to know one.
+C is full of holes, let's get to know one.
 
-- Old skool, so no OS or hardware protections.
+Old skool, so no OS or hardware protections. Which today is mostly relevant in IoT. (Remember, the `S` in `IoT` stands for Security.)
+
+Stack smashing is making use of a buffer overflow vulnerability in code using variables on the stack. This type of vulenrability has been known for a long time. This attack was first properly documented in Phrack #49.
+
+.footnote[Phrack #49(http://www.phrack.org/issues/49/14.html#article)]
 ]
 ---
 template: inverse
@@ -171,6 +175,22 @@ For x86 systems the stack grows from the largest memory address up.
 .footnote[Borrowed from [wikipedia](https://en.wikipedia.org/wiki/Stack-based_memory_allocation)]
 ]
 ---
+.left-column[
+## Say wut?
+]
+.right-column[
+Whenever a function is called a frame is added to the stack. Whenever a function ends the frame is deleted.
+
+Such a frame consists of variables, a stored stack pointer and a return address.
+]
+---
+.left-column[
+## This is not helping you know...
+]
+.right-column.center.middle[
+<img src="Stack.png" width="100%" />
+]
+---
 template: inverse
 # How does this work?
 ---