Let’s break down the concepts of stack overflow and heap overflow—two powerful and potentially dangerous types of memory vulnerabilities in computing.

🧠 What Is the Stack?

The stack is a region of memory used for:

• Function calls
• Local variables
• Return addresses

It’s LIFO (Last In, First Out) and grows downward in most systems.

💥 Stack Overflow

A stack overflow occurs when a program uses more stack space than is available, often due to:

• Deep or infinite recursion
• Large local arrays
• Unchecked input

🔧 Example in C++:

void recurse() {
    int buffer[10000];  // Large local array
    recurse();          // Infinite recursion
}

int main() {
    recurse();
}

This will crash with a stack overflow, as each recursive call consumes more stack space.

🧠 What Is the Heap?

The heap is a region of memory used for:

• Dynamically allocated memory (new, malloc)
• Objects with flexible lifetimes

It’s managed manually (in C/C++) or automatically (in languages like Python or Java).

💥 Heap Overflow

A heap overflow happens when a program writes beyond the bounds of a dynamically allocated block.

🔧 Example in C++:

char* buffer = new char[10];
strcpy(buffer, "This string is way too long!");  // Overflows heap memory

This writes past the allocated 10 bytes, potentially corrupting adjacent heap structures.

⚠️ Why Are These Dangerous?

Attackers can use these to:

• Inject shellcode
• Hijack control flow
• Escalate privileges

🛡️ How to Prevent Them

• Use safe functions (strncpy, fgets)
• Validate input sizes
• Enable compiler protections (-fstack-protector, ASLR, DEP)
• Use memory-safe languages (Rust, Python, Java)