From a0f775683d289dd517781d70c5962916bc4f2113 Mon Sep 17 00:00:00 2001
From: Lee Rowlands <lee.rowlands@previousnext.com.au>
Date: Thu, 7 Nov 2024 11:49:11 +1000
Subject: [PATCH] Fix recursion when arrays contain self-references in
 sandboxed mode

---
 src/Extension/SandboxExtension.php | 11 ++++++++++-
 tests/Extension/SandboxTest.php    | 12 ++++++++----
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/Extension/SandboxExtension.php b/src/Extension/SandboxExtension.php
index 95b6295aa2..9603f8e975 100644
--- a/src/Extension/SandboxExtension.php
+++ b/src/Extension/SandboxExtension.php
@@ -26,11 +26,14 @@ final class SandboxExtension extends AbstractExtension
     private $policy;
     private $sourcePolicy;
 
+    static array $recursionProjection = [];
+
     public function __construct(SecurityPolicyInterface $policy, $sandboxed = false, ?SourcePolicyInterface $sourcePolicy = null)
     {
         $this->policy = $policy;
         $this->sandboxedGlobally = $sandboxed;
         $this->sourcePolicy = $sourcePolicy;
+        static::$recursionProjection = [];
     }
 
     public function getTokenParsers(): array
@@ -120,10 +123,16 @@ public function checkPropertyAllowed($obj, $property, int $lineno = -1, ?Source
     public function ensureToStringAllowed($obj, int $lineno = -1, ?Source $source = null)
     {
         if (\is_array($obj)) {
+            $hash = \hash('sha256', \serialize($obj));
+            if (\array_key_exists($hash, static::$recursionProjection)) {
+                unset(static::$recursionProjection[$hash]);
+                return $obj;
+            }
+            static::$recursionProjection[$hash] = TRUE;
             foreach ($obj as $v) {
                 $this->ensureToStringAllowed($v, $lineno, $source);
             }
-
+            unset(static::$recursionProjection[$hash]);
             return $obj;
         }
 
diff --git a/tests/Extension/SandboxTest.php b/tests/Extension/SandboxTest.php
index cc74e8cd56..647ea29534 100644
--- a/tests/Extension/SandboxTest.php
+++ b/tests/Extension/SandboxTest.php
@@ -41,7 +41,10 @@ protected function setUp(): void
             'some_array' => [5, 6, 7, new FooObject()],
             'array_like' => new ArrayLikeObject(),
             'magic' => new MagicObject(),
+            'recursion' => [4],
         ];
+        self::$params['recursion'][] = &self::$params['recursion'];
+        self::$params['recursion'][] = new FooObject();
 
         self::$templates = [
             '1_basic1' => '{{ obj.foo }}',
@@ -240,6 +243,7 @@ public function getSandboxUnallowedToStringTests()
             'context' => ['{{ _context|join(", ") }}'],
             'spread_array_operator' => ['{{ [1, 2, ...[5, 6, 7, obj]]|join(",") }}'],
             'spread_array_operator_var' => ['{{ [1, 2, ...some_array]|join(",") }}'],
+            'recursion' => ['{{ recursion|join(", ") }}'],
         ];
     }
 
@@ -573,13 +577,13 @@ class ArrayLikeObject extends \ArrayObject
 {
     public function offsetExists($offset): bool
     {
-        throw new \BadMethodCallException('Should not be called');
+        throw new \BadMethodCallException('Should not be called.');
     }
 
     #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
-        throw new \BadMethodCallException('Should not be called');
+        throw new \BadMethodCallException('Should not be called.');
     }
 
     public function offsetSet($offset, $value): void
@@ -596,11 +600,11 @@ class MagicObject
     #[\ReturnTypeWillChange]
     public function __get($name)
     {
-        throw new \BadMethodCallException('Should not be called');
+        throw new \BadMethodCallException('Should not be called.');
     }
 
     public function __isset($name): bool
     {
-        throw new \BadMethodCallException('Should not be called');
+        throw new \BadMethodCallException('Should not be called.');
     }
 }