Create temp working directory for each libfuzzer invocation

src/agent/coverage/fuzz/Cargo.toml

@@ -9,7 +9,7 @@ cargo-fuzz = true
 
 [dependencies]
 libfuzzer-sys = "0.4"
-tempfile = "3.7"
+tempfile = "3.8"
 debuggable-module = { path = "../../debuggable-module" }
 
 
@@ -34,4 +34,3 @@ name = "fuzz_target_allowlist_parse"
 path = "fuzz_targets/fuzz_target_allowlist_parse.rs"
 test = false
 doc = false
-

src/agent/onefuzz-agent/Cargo.toml

@@ -40,6 +40,7 @@ azure_storage = { version = "0.15", default-features = false, features = [
 azure_storage_blobs = { version = "0.15", default-features = false, features = [
     "enable_reqwest",
 ] }
+tempfile = "3.8"
 
 
 [target.'cfg(target_family = "unix")'.dependencies]

src/agent/onefuzz-agent/src/validations.rs

@@ -101,6 +101,7 @@ async fn run_setup(setup_folder: impl AsRef<Path>) -> Result<()> {
 }
 
 async fn get_logs(config: ValidationConfig) -> Result<()> {
+    let tmp_working_dir = tempfile::tempdir()?;
     let setup_folder = config
         .setup_folder
         .clone()
@@ -121,7 +122,7 @@ async fn get_logs(config: ValidationConfig) -> Result<()> {
         },
     );
 
-    let cmd = libfuzzer.build_std_command(None, None, None, None, None)?;
+    let cmd = libfuzzer.build_std_command(tmp_working_dir.path(), None, None, None, None, None)?;
     print_logs(cmd)?;
     Ok(())
 }

src/agent/onefuzz-task/src/tasks/fuzz/libfuzzer/common.rs

@@ -257,6 +257,7 @@ where
         worker_id: usize,
         stats_sender: Option<&StatsSender>,
     ) -> Result<()> {
+        let tmp_working_dir = self.create_local_temp_dir().await?;
         let crash_dir = self.create_local_temp_dir().await?;
         let run_id = Uuid::new_v4();
 
@@ -272,7 +273,12 @@ where
         info!("config is: {:?}", self.config);
 
         let fuzzer = L::from_config(&self.config).await?;
-        let mut running = fuzzer.fuzz(crash_dir.path(), local_inputs, &inputs)?;
+        let mut running = fuzzer.fuzz(
+            tmp_working_dir.path(),
+            crash_dir.path(),
+            local_inputs,
+            &inputs,
+        )?;
 
         info!("child is: {:?}", running);
 
@@ -376,22 +382,22 @@ where
             // note that collecting the dumps must be enabled by the template
             #[cfg(target_os = "linux")]
             if let Some(pid) = pid {
-                // expect crash dump to exist in CWD
-                let filename = format!("core.{pid}");
+                // expect crash dump to exist in fuzzer (temp) working dir
+                let filename = tmp_working_dir.path().join(format!("core.{pid}"));
                 let dest_filename = dump_file_name.as_deref().unwrap_or(OsStr::new(&filename));
                 let dest_path = crashdumps.local_path.join(dest_filename);
                 match tokio::fs::rename(&filename, &dest_path).await {
                     Ok(()) => {
                         info!(
                             "moved crash dump {} to output directory: {}",
-                            filename,
+                            filename.display(),
                             dest_path.display()
                         );
                     }
                     Err(e) => {
                         if e.kind() == std::io::ErrorKind::NotFound {
                             // okay, no crash dump found
-                            info!("no crash dump found with name: {}", filename);
+                            info!("no crash dump found with name: {}", filename.display());
                         } else {
                             return Err(e).context("moving crash dump to output directory");
                         }
@@ -406,7 +412,7 @@ where
             {
                 let dumpfile_extension = Some(std::ffi::OsStr::new("dmp"));
 
-                let mut working_dir = tokio::fs::read_dir(".").await?;
+                let mut working_dir = tokio::fs::read_dir(tmp_working_dir.path()).await?;
                 let mut found_dump = false;
                 while let Some(next) = working_dir.next_entry().await? {
                     if next.path().extension() == dumpfile_extension {

src/agent/onefuzz/src/libfuzzer.rs

@@ -70,13 +70,15 @@ impl LibFuzzer {
     // Build an async `Command`.
     fn build_command(
         &self,
+        working_dir: &Path,
         fault_dir: Option<&Path>,
         corpus_dir: Option<&Path>,
         extra_corpus_dirs: Option<&[&Path]>,
         extra_args: Option<&[&OsStr]>,
         custom_arg_filter: Option<&dyn Fn(String) -> Option<String>>,
     ) -> Result<Command> {
         let std_cmd = self.build_std_command(
+            working_dir,
             fault_dir,
             corpus_dir,
             extra_corpus_dirs,
@@ -96,13 +98,20 @@ impl LibFuzzer {
     // Build a non-async `Command`.
     pub fn build_std_command(
         &self,
+        working_dir: &Path,
         fault_dir: Option<&Path>,
         corpus_dir: Option<&Path>,
         extra_corpus_dirs: Option<&[&Path]>,
         extra_args: Option<&[&OsStr]>,
         custom_arg_filter: Option<&dyn Fn(String) -> Option<String>>,
     ) -> Result<std::process::Command> {
         let mut cmd = std::process::Command::new(&self.exe);
+
+        // subprocess is isolated in its own working directory
+        // this is to prevent collisions between multiple libfuzzers
+        // (for example, crash dumps are generated into working directory on Windows)
+        cmd.current_dir(working_dir);
+
         cmd.env(PATH, get_path_with_directory(PATH, &self.setup_dir)?)
             .env_remove("RUST_LOG")
             .stdin(Stdio::null())
@@ -250,7 +259,9 @@ impl LibFuzzer {
     // Verify that the libfuzzer exits with a zero return code with a known
     // good input, which libfuzzer works as we expect.
     async fn check_input(&self, input: &Path) -> Result<()> {
+        let tmp_working_dir = tempdir()?;
         let mut cmd = self.build_command(
+            tmp_working_dir.path(),
             None,
             None,
             None,
@@ -294,7 +305,15 @@ impl LibFuzzer {
     /// least able to satisfy the fuzzer's shared library dependencies. User-authored
     /// dynamic loading may still fail later on, e.g. in `LLVMFuzzerInitialize()`.
     async fn check_help(&self) -> Result<()> {
-        let mut cmd = self.build_command(None, None, None, Some(&["-help=1".as_ref()]), None)?;
+        let tmp_working_dir = tempdir()?;
+        let mut cmd = self.build_command(
+            tmp_working_dir.path(),
+            None,
+            None,
+            None,
+            Some(&["-help=1".as_ref()]),
+            None,
+        )?;
 
         let result = cmd
             .spawn()
@@ -326,7 +345,8 @@ impl LibFuzzer {
     }
 
     async fn find_missing_libraries(&self) -> Result<(Vec<String>, Vec<String>)> {
-        let cmd = self.build_std_command(None, None, None, None, None)?;
+        let tmp_working_dir = tempdir()?;
+        let cmd = self.build_std_command(tmp_working_dir.path(), None, None, None, None, None)?;
 
         #[cfg(target_os = "linux")]
         let blocking = move || dynamic_library::linux::find_missing(cmd);
@@ -343,6 +363,7 @@ impl LibFuzzer {
 
     pub fn fuzz(
         &self,
+        working_dir: &Path,
         fault_dir: impl AsRef<Path>,
         corpus_dir: impl AsRef<Path>,
         extra_corpus_dirs: &[impl AsRef<Path>],
@@ -357,6 +378,7 @@ impl LibFuzzer {
         let artifact_prefix = artifact_prefix(fault_dir.as_ref());
 
         let mut cmd = self.build_command(
+            working_dir,
             Some(fault_dir.as_ref()),
             Some(corpus_dir.as_ref()),
             Some(&extra_corpus_dirs),
@@ -406,8 +428,10 @@ impl LibFuzzer {
         corpus_dir: impl AsRef<Path>,
         extra_corpus_dirs: &[impl AsRef<Path>],
     ) -> Result<LibFuzzerMergeOutput> {
+        let tmp_working_dir = tempdir()?;
         let extra_corpus_dirs: Vec<&Path> = extra_corpus_dirs.iter().map(|x| x.as_ref()).collect();
         let mut cmd = self.build_command(
+            tmp_working_dir.path(),
             None,
             Some(corpus_dir.as_ref()),
             Some(&extra_corpus_dirs),