• Execution flow
• Memory management
  • Memory layout
  • Common memory bugs
    • Segmentation fault
    • Stack overflow
• Dependency management
• References

Execution flow

1. The GNU Compiler Collection (GCC) converts our C code into an assembly specific to our CPU architecture like x86_64, amd64, arm64.
2. The assembler compiles the assembly into a group of binaries, also called object files.
3. The linker combines the object files and libraries into the final binary.
4. The machine executes the final binary.

Memory management

Memory layout

Below is the memory layout listed from top to bottom in the memory space.

• Kernel space
  • Accessing this region causes segmentation fault.
• Stack
  • Include function calls and local variables.
  • Deep recursion causes stack overflow.
  • Grow downward.
• Unused memory
• Heap
  • Malloc/new dynamic allocations
  • Invalid free/dereferencing causes segmentation fault.
  • Grow upward.
• BSS
  • Uninitialized global variables
• Data
  • Initialized global variables
• Text
  • Compiled code
• NULL (memory address 0x0)
  • Dereferencing this causes segmentation fault.

Common memory bugs

Segmentation fault

A segmentation fault occurs when a program tries to access a memory region it is not allowed to. Some examples are listed below.

• Read/write outside of array bounds
• Use/free a null pointer
• Use-after-free
• Double free

Stack overflow

A stack overflow happens when a program uses too much stack memory. Some examples are listed below.

• Deep recursion
• Large local variable allocation

Dependency management

References