Fixed infinite loop in case of a recursive pages dictionary

Author: MaximilianKresse

src/PdfReader/PdfReader.php

@@ -139,12 +139,19 @@ public function getPage($pageNumber)
         $page = $this->pages[$pageNumber - 1];
 
         if ($page instanceof PdfIndirectObjectReference) {
-            $readPages = function ($kids) use (&$readPages) {
+            $alreadyReadKids = [];
+            $readPages = function ($kids) use (&$readPages, &$alreadyReadKids) {
                 $kids = PdfArray::ensure($kids);
 
                 /** @noinspection LoopWhichDoesNotLoopInspection */
                 foreach ($kids->value as $reference) {
                     $reference = PdfIndirectObjectReference::ensure($reference);
+
+                    if (\in_array($reference->value, $alreadyReadKids)) {
+                        throw new PdfReaderException('Recursive pages dictionary detected.');
+                    }
+                    $alreadyReadKids[] = $reference->value;
+
                     $object = $this->parser->getIndirectObject($reference->value);
                     $type = PdfDictionary::get($object->value, 'Type');
 
@@ -168,6 +175,7 @@ public function getPage($pageNumber)
             if ($type->value === 'Pages') {
                 $kids = PdfType::resolve(PdfDictionary::get($dict, 'Kids'), $this->parser);
                 try {
+                    $alreadyReadKids[] = $page->objectNumber;
                     $page = $this->pages[$pageNumber - 1] = $readPages($kids);
                 } catch (PdfReaderException $e) {
                     if ($e->getCode() !== PdfReaderException::KIDS_EMPTY) {
@@ -203,7 +211,8 @@ protected function readPages($readAll = false)
         }
 
         $expectedPageCount = $this->getPageCount();
-        $readPages = function ($kids, $count) use (&$readPages, $readAll, $expectedPageCount) {
+        $alreadyReadKids = [];
+        $readPages = function ($kids, $count) use (&$readPages, &$alreadyReadKids, $readAll, $expectedPageCount) {
             $kids = PdfArray::ensure($kids);
             $isLeaf = ($count->value === \count($kids->value));
 
@@ -215,6 +224,11 @@ protected function readPages($readAll = false)
                     continue;
                 }
 
+                if (\in_array($reference->value, $alreadyReadKids)) {
+                    throw new PdfReaderException('Recursive pages dictionary detected.');
+                }
+                $alreadyReadKids[] = $reference->value;
+
                 $object = $this->parser->getIndirectObject($reference->value);
                 $type = PdfDictionary::get($object->value, 'Type');