bug #29884 [Form] CsrfValidationListener marks the token as invalid if it is not a string (umpirsky)

This PR was squashed before being merged into the 3.4 branch (closes #29884).

Discussion
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[Form] CsrfValidationListener marks the token as invalid if it is not a string

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #29882
| License       | MIT

Commits
-------

deb8e95091 [Form] CsrfValidationListener marks the token as invalid if it is not a string

Author: nicolas-grekas

Extension/Csrf/EventListener/CsrfValidationListener.php

@@ -59,7 +59,7 @@ public function preSubmit(FormEvent $event)
         if ($form->isRoot() && $form->getConfig()->getOption('compound') && !$postRequestSizeExceeded) {
             $data = $event->getData();
 
-            if (!isset($data[$this->fieldName]) || !$this->tokenManager->isTokenValid(new CsrfToken($this->tokenId, $data[$this->fieldName]))) {
+            if (!isset($data[$this->fieldName]) || !\is_string($data[$this->fieldName]) || !$this->tokenManager->isTokenValid(new CsrfToken($this->tokenId, $data[$this->fieldName]))) {
                 $errorMessage = $this->errorMessage;
 
                 if (null !== $this->translator) {

Tests/Extension/Csrf/EventListener/CsrfValidationListenerTest.php

@@ -64,6 +64,16 @@ public function testStringFormData()
         $this->assertSame($data, $event->getData());
     }
 
+    public function testArrayCsrfToken()
+    {
+        $event = new FormEvent($this->form, ['csrf' => []]);
+
+        $validation = new CsrfValidationListener('csrf', $this->tokenManager, 'unknown', 'Invalid.');
+        $validation->preSubmit($event);
+
+        $this->assertNotEmpty($this->form->getErrors());
+    }
+
     public function testMaxPostSizeExceeded()
     {
         $serverParams = $this