oss-fuzz/docs/fuzzer_environment.md

Fuzzer environment on ClusterFuzz

Your fuzzers will be run on a Google Compute Engine VM (Linux) with some security restrictions.

Current working directory

You should not make any assumptions about the current working directory of your fuzzer. If you need to load data files, please use argv[0] to get the directory where your fuzzer executable is located.

Filesystem

Everything except /tmp is read-only, including the directory that your fuzzer executable lives in. Note that /tmp is limited in size (64MB).

Network access

There will be no network interfaces available (not even loopback).