CMU 15-213 · Computer Systems

CS:APP Lab Notes¶

From a single bit flip to a concurrent web proxy. Source-backed notes on the implementations, design choices, and the why behind them.

Start with Data Lab → Source on GitHub

The Labs¶

01 · Data btest 36/36

Data Lab ¶

Integer and floating-point operations built from bitwise primitives only, under strict operator-count limits.
02 · Reverse Eng. defused

Bomb Lab ¶

Defusing a binary bomb phase by phase in GDB, reading x86-64 assembly, and cracking a hidden stage backed by a binary tree.
03 · Exploits 5/5 pass

Attack Lab ¶

Hijacking control flow through stack buffer overflows — from code injection to a ROP chain that defeats NX and ASLR.
04 · Memory 53/61

Cache Lab ¶

An LRU cache simulator written from scratch, then a blocked matrix transpose tuned to drive misses to the floor.
05 · Processes 16/16 traces

Shell Lab ¶

A job-control Unix shell, with signal masking around the fork/addjob race.
06 · Allocation 97/100

Malloc Lab ¶

malloc/free/realloc from the ground up, six designs deep — from one implicit list to twelve segregated rings.
07 · Networking 70/70

Proxy Lab ¶

An HTTP proxy that parses absolute URIs, rewrites hop-by-hop headers, and caches full responses under an approximate LRU policy.
08 · File Systems 22/22 · AI-assisted

SFS Lab ¶

A small mmap-backed file system with atomic rename, open-file lifetime tracking, and per-file locking that scales past the global baseline.

About these notes

The first seven entries follow CMU's Computer Systems: A Programmer's Perspective (3^rd ed.); SFS Lab is a separate file-system extension and is explicitly marked as AI-assisted. Every completed solution was run against its grader, with the result shown at the top of the writeup.