Gain insights into using GDB for debugging in Linux. Explore disassembly, memory investigation, and register updates. Learn about pointers, stack, and function parameters in x64 architecture.

gdb.tar.gz

C2-LA

C4-L2

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test

GNU Debugger (GDB) is used for debugging C/C++ programs in LINUX/UNIX environments. It is a good tool to investigate what is happening inside a program, and how the contents inside the memory are changed with the execution of the program.

The main focus of the course is the disassembly of the program, where we'll use simple operations in C. With the help of GDB, we'll examine the contents of the registers and memory. We'll also learn how they are changed while executing basic operations. We’ll then explore the use of pointers, stack, and function parameters, and analyze how different registers update their values. With the help of disassembly output, we’ll learn how a simple C program can be reconstructed. The disassembly output is important for debugging and core dump analysis. We’ll use assembly language for x64 architecture.

By the end of this course, you should be able to debug the programs and memory contents at assembly level when a program executes or probe into the problem when a program crashes.

Debugging, Disassembly & Reversing in Linux for x64 Architecture

## Stack
A stack is a _simple computational device_ with two operations:
* `push` 
* `pop` 

These operations allow us to pile up data to remember it in **LIFO (last in first out)** manner, and quickly retrieve the last piled data item as shown below:

## Stack implementation in memory
The CPU register `%RSP` (**Stack Pointer**) points to the top of a stack. In the figure below, a stack grows towards lower memory addresses with every `push` operation. This is implemented as _decrementing the `%RSP` register by 8_.

We can read the top stack value using the following instruction:
```asm
mov (%rsp), %rax
```

# Stack
A stack is a _simple computational device_ with two operations:
* `push` 
* `pop` 

These operations allow us to pile up data to remember it in **LIFO (last in first out)** manner, and quickly retrieve the last piled data item as shown below:

# Stack implementation in memory
The CPU register `%RSP` (**Stack Pointer**) points to the top of a stack. In the figure below, a stack grows towards lower memory addresses with every `push` operation. This is implemented as _decrementing the `%RSP` register by 8_.

We can read the top stack value using the following instruction:
```asm
mov (%rsp), %rax
```

Introduction to the Course

Memory, Registers, and Simple Arithmetic

Code Optimization

Number Representations

Pointers

Bytes, Words, Double, and Quad Words

Pointers to Memory

Logical Instructions and RIP

Reconstructing a Program with Pointers

Memory and Stacks

Frame Pointer and Local Variables

Function Parameters

More Instructions

Function Pointer Parameters

Summary of Code Disassembly Patterns

x64 Debugging, Disassembly & Reversing Exam

Introduction to Stack

Stack

Stack implementation in memory