ch10 Issues w/ Book and Code

[sandstkj]

I spent a long time getting started with chapter 10.

1. In this code base, meet.c should have return 0; at the end of the main function. Granted, I don't know exactly why this fixes the problem (if you're overwriting the EIP in the stack of a function, why would a missing return in main affect this?). All I know is the book has a return for main, and adding it fixed this code for me.

2. Code in the book is written like python2 but has instructions to use python 3. These small examples are only written in the book, and are not in this repository, so I don't think there's anything to fix on this side.

Example of the problem: (gdb) run Mr python -c 'print("A"*600)'
Should be: (gdb) run Mr python -c 'print(b"A"*600)'

[htejeda]

Hi @sandstkj , thanks for sharing your experience!

I went through Chapter 10 again and wanted to share a few clarifications that might help:

• At the time of writing, we used Kali 2022.1, which includes Python 3.9.10 by default. In this lab, we just specified python, but we should've explicitly written python2, since this is an old-school buffer overflow step-by-step example and was designed for Python 2.
• As a bonus, we added a modern exploit using Pwntools with Python 3, available here: meet_exploit.py
• Regarding return 0, since main() is declared to return an integer, including it explicitly just ensures a clean and proper exit. Technically, omitting it is undefined behavior in C, though most compilers handle it gracefully. I tested both the Python 2 step-by-step and the Python 3 meet_exploit.py script with and without return 0, and both worked fine.

So it's likely the issue came from mixing Python versions or how the payload was passed. Glad you got it working though!