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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C8-L1

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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

# Local variables project
Let’s learn more about local variables with a project.

## Source code
The source code of the local variables project is given below:


int main()
{
	int a, b;

	a = 1;
	b = 1;

	b = b + a;
	++a;
	b = b * a;

	return 0;
}

## Compilation and execution of code
We compile the file and load the executable into GDB:
```s
gcc LocalVariables.cpp -o LocalVariables
gdb ./LocalVariables
```


The output after loading the executable file:

Then we put a breakpoint to the `main`:
```s
break main
```
The `breakpoint` of the function is displayed below:

Learn how local variables work in functions.

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

Local Variables

Local variables project

Source code

Compilation and execution of code