Merge pull request #1224 from dtolnay/fuzz

Add fuzz target for TokenBuffer and file parse

.github/workflows/ci.yml

@@ -108,6 +108,15 @@ jobs:
       - run: cargo update -Z minimal-versions
       - run: cargo check --all-features
 
+  fuzz:
+    name: Fuzz
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dtolnay/rust-toolchain@nightly
+      - uses: dtolnay/install@cargo-fuzz
+      - run: cargo fuzz build -O
+
   miri:
     name: Miri
     runs-on: ubuntu-latest
@@ -137,3 +146,4 @@ jobs:
       - uses: actions/checkout@v3
       - uses: dtolnay/install@cargo-outdated
       - run: cargo outdated --workspace --exit-code 1
+      - run: cargo outdated --manifest-path fuzz/Cargo.toml --exit-code 1

fuzz/.gitignore

@@ -0,0 +1,3 @@
+artifacts/
+corpus/
+target/

fuzz/Cargo.toml

@@ -0,0 +1,28 @@
+[package]
+name = "syn-fuzz"
+version = "0.0.0"
+authors = ["David Tolnay <dtolnay@gmail.com>"]
+edition = "2021"
+publish = false
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+libfuzzer-sys = "0.4"
+proc-macro2 = "1"
+syn = { path = "..", default-features = false, features = ["full", "parsing"] }
+
+[[bin]]
+name = "create_token_buffer"
+path = "fuzz_targets/create_token_buffer.rs"
+test = false
+doc = false
+
+[[bin]]
+name = "parse_file"
+path = "fuzz_targets/parse_file.rs"
+test = false
+doc = false
+
+[workspace]

fuzz/fuzz_targets/create_token_buffer.rs

@@ -0,0 +1,18 @@
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+use proc_macro2::Span;
+use std::str;
+use syn::parse::{ParseStream, Parser};
+
+fn immediate_fail(_input: ParseStream) -> syn::Result<()> {
+    Err(syn::Error::new(Span::call_site(), ""))
+}
+
+fuzz_target!(|data: &[u8]| {
+    if data.len() < 300 {
+        if let Ok(string) = str::from_utf8(data) {
+            _ = immediate_fail.parse_str(string);
+        }
+    }
+});

fuzz/fuzz_targets/parse_file.rs

@@ -0,0 +1,12 @@
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+use std::str;
+
+fuzz_target!(|data: &[u8]| {
+    if data.len() < 300 {
+        if let Ok(string) = str::from_utf8(data) {
+            _ = syn::parse_file(string);
+        }
+    }
+});