char c = *p;

What could be more complicated than a simple pointer dereference? It might translate to some innocent looking machine code:

  40122a:       0f b6 00                movzx  eax,BYTE PTR [rax]

But don't let appearances fool you! On a modern machine, these three bytes can invoke arbitrary Python code just to read a byte out of memory. How?

1. mmap() can be used to map the contents of a file into memory
2. Linux will not actually read anything from the file before we need to
3. Filesystem-in-userspace (FUSE) is used to implement a file system driver in Python

Try it yourself! Install the Python package fusepy and run fs.py. It will create a directory fuse-dir, where all paths are files containing the bytes pointer schmointer\n. Compile and run main.c, and when you hit enter, the C code will dereference a pointer and Python code will run.