Fix recursive call leading to stack overflow when tracing level filter is TRACE (#3312)

myFavShrimp · web-flow · commit 6bf1fcbb294d · 2025-04-24T13:03:50.000+02:00
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/axum-extra/Cargo.toml b/axum-extra/Cargo.toml
@@ -38,7 +38,7 @@ multipart = ["dep:multer", "dep:fastrand"]
 protobuf = ["dep:prost"]
 scheme = []
 query = ["dep:form_urlencoded", "dep:serde_html_form", "dep:serde_path_to_error"]
-tracing = ["axum-core/tracing", "axum/tracing"]
+tracing = ["axum-core/tracing", "axum/tracing", "dep:tracing"]
 typed-header = ["dep:headers"]
 typed-routing = ["dep:axum-macros", "dep:percent-encoding", "dep:serde_html_form", "dep:form_urlencoded"]
 
@@ -92,6 +92,7 @@ serde_json = "1.0.71"
 tokio = { version = "1.14", features = ["full"] }
 tower = { version = "0.5.2", features = ["util"] }
 tower-http = { version = "0.6.0", features = ["map-response-body", "timeout"] }
+tracing-subscriber = "0.3.19"
 
 [lints]
 workspace = true
diff --git a/axum-extra/src/extract/multipart.rs b/axum-extra/src/extract/multipart.rs
@@ -243,12 +243,13 @@ impl MultipartError {
 
     /// Get the response body text used for this rejection.
     pub fn body_text(&self) -> String {
+        let body = self.source.to_string();
         axum_core::__log_rejection!(
             rejection_type = Self,
-            body_text = self.body_text(),
+            body_text = body,
             status = self.status(),
         );
-        self.source.to_string()
+        body
     }
 
     /// Get the status code used for this rejection.
@@ -398,4 +399,43 @@ mod tests {
         let res = client.post("/").multipart(form).await;
         assert_eq!(res.status(), StatusCode::PAYLOAD_TOO_LARGE);
     }
+
+    #[tokio::test]
+    #[cfg(feature = "tracing")]
+    async fn body_too_large_with_tracing() {
+        const BYTES: &[u8] = "<!doctype html><title>🦀</title>".as_bytes();
+
+        async fn handle(mut multipart: Multipart) -> impl IntoResponse {
+            let result: Result<(), MultipartError> = async {
+                while let Some(field) = multipart.next_field().await? {
+                    field.bytes().await?;
+                }
+                Ok(())
+            }
+            .await;
+
+            let subscriber = tracing_subscriber::FmtSubscriber::builder()
+                .with_max_level(tracing::level_filters::LevelFilter::TRACE)
+                .with_writer(std::io::sink)
+                .finish();
+
+            let guard = tracing::subscriber::set_default(subscriber);
+            let response = result.into_response();
+            drop(guard);
+
+            response
+        }
+
+        let app = Router::new()
+            .route("/", post(handle))
+            .layer(DefaultBodyLimit::max(BYTES.len() - 1));
+
+        let client = TestClient::new(app);
+
+        let form =
+            reqwest::multipart::Form::new().part("file", reqwest::multipart::Part::bytes(BYTES));
+
+        let res = client.post("/").multipart(form).await;
+        assert_eq!(res.status(), StatusCode::PAYLOAD_TOO_LARGE);
+    }
 }
