Fix possible stack overflow in validator.

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+# [3.0.27] 2022-1-28
+
+- Fix possible stack overflow in validator, thanks @quapka.
+
 # [3.0.26] 2022-1-26
 
 - Add `skip_input` attribute to `InputObject` macro, `skip_output` attribute to `SimpleObject` macro.

SECURITY.md

@@ -2,9 +2,9 @@
 
 ## Supported Versions
 
-| Version | Supported          |
-| ------- | ------------------ |
-| >= 3.0.0 | :white_check_mark:                |
+| Version  | Supported          |
+|----------|--------------------|
+| >= 3.0.0 | :white_check_mark: |
 
 ## Reporting a Vulnerability
 

src/validation/rules/overlapping_fields_can_be_merged.rs

@@ -1,4 +1,4 @@
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 
 use crate::parser::types::{Field, Selection, SelectionSet};
 use crate::validation::visitor::{Visitor, VisitorContext};
@@ -15,6 +15,7 @@ impl<'a> Visitor<'a> for OverlappingFieldsCanBeMerged {
     ) {
         let mut find_conflicts = FindConflicts {
             outputs: Default::default(),
+            visited: Default::default(),
             ctx,
         };
         find_conflicts.find(selection_set);
@@ -23,6 +24,7 @@ impl<'a> Visitor<'a> for OverlappingFieldsCanBeMerged {
 
 struct FindConflicts<'a, 'ctx> {
     outputs: HashMap<&'a str, &'a Positioned<Field>>,
+    visited: HashSet<&'a str>,
     ctx: &'a mut VisitorContext<'ctx>,
 }
 
@@ -46,6 +48,13 @@ impl<'a, 'ctx> FindConflicts<'a, 'ctx> {
                     if let Some(fragment) =
                         self.ctx.fragment(&fragment_spread.node.fragment_name.node)
                     {
+                        if !self
+                            .visited
+                            .insert(fragment_spread.node.fragment_name.node.as_str())
+                        {
+                            // To avoid recursing itself, this error is detected by the `NoFragmentCycles` validator.
+                            continue;
+                        }
                         self.find(&fragment.node.selection_set);
                     }
                 }

tests/simple_object.rs

@@ -54,3 +54,51 @@ async fn test_flatten() {
         })
     );
 }
+
+#[tokio::test]
+async fn recursive_fragment_definition() {
+    #[derive(SimpleObject)]
+    struct Hello {
+        world: String,
+    }
+
+    struct Query;
+
+    // this setup is actually completely irrelevant we just need to be able ot execute a query
+    #[Object]
+    impl Query {
+        async fn obj(&self) -> Hello {
+            Hello {
+                world: "Hello World".into(),
+            }
+        }
+    }
+
+    let schema = Schema::new(Query, EmptyMutation, EmptySubscription);
+    let query = "fragment f on Query {...f} { __typename }";
+    assert!(schema.execute(query).await.into_result().is_err());
+}
+
+#[tokio::test]
+async fn recursive_fragment_definition_nested() {
+    #[derive(SimpleObject)]
+    struct Hello {
+        world: String,
+    }
+
+    struct Query;
+
+    // this setup is actually completely irrelevant we just need to be able ot execute a query
+    #[Object]
+    impl Query {
+        async fn obj(&self) -> Hello {
+            Hello {
+                world: "Hello World".into(),
+            }
+        }
+    }
+
+    let schema = Schema::new(Query, EmptyMutation, EmptySubscription);
+    let query = "fragment f on Query { a { ...f a { ...f } } } { __typename }";
+    assert!(schema.execute(query).await.into_result().is_err());
+}