MDL-79819 assignfeedback_editpdf: safely handle bad jpg->pdf conversion

mod/assign/feedback/editpdf/classes/document_services.php

@@ -1033,7 +1033,7 @@ EOD;
      * @param int $attemptnumber Attempt Number
      * @param \stored_file $file file to save
      * @param null|array $size size of image
-     * @return \stored_file
+     * @return null|\stored_file
      * @throws \file_exception
      * @throws \stored_file_creation_exception
      */
@@ -1059,14 +1059,21 @@ EOD;
         $pdf->setImageScale(PDF_IMAGE_SCALE_RATIO);
         $pdf->AddPage($orientation);
         $pdf->SetAutoPageBreak(false);
-        // Width has to be define here to fit into A4 page. Otherwise the image will be inserted with original size.
-        if ($orientation == 'P') {
-            $pdf->Image('@' . $file->get_content(), 0, 0, 210);
-        } else {
-            $pdf->Image('@' . $file->get_content(), 0, 0, 297);
+        try {
+            // Width has to be defined here to fit into an A4 page, otherwise the image will be inserted with original size.
+            if ($orientation == 'P') {
+                $pdf->Image('@' . $file->get_content(), 0, 0, 210);
+            } else {
+                $pdf->Image('@' . $file->get_content(), 0, 0, 297);
+            }
+            $pdf->setPageMark();
+            $pdf->save_pdf($tempfile);
+        } catch (\Exception $e) {
+            // Trim off the binary image data in the exception message for debugging output.
+            $exceptionmsg = strstr($e->getMessage(), '@', true) ?: $e->getMessage();
+            debugging("Could not convert {$file->get_contenthash()} jpg to pdf: {$exceptionmsg}", DEBUG_ALL);
+            return null;
         }
-        $pdf->setPageMark();
-        $pdf->save_pdf($tempfile);
         $filearea = self::TMP_JPG_TO_PDF_FILEAREA;
         $pdffile = self::save_file($assignment, $userid, $attemptnumber, $filearea, $tempfile);
         if (file_exists($tempfile)) {

mod/assign/feedback/editpdf/tests/document_services_test.php

@@ -89,6 +89,39 @@ final class document_services_test extends \advanced_testcase {
         $this->assertEquals($file1->get_id(), $file2->get_id());
     }
 
+    /**
+     * Test that save_jpg_to_pdf() method safely rejects a non-JPEG file with a JPEG extension.
+     */
+    public function test_save_jpg_to_pdf_rejects_non_jpeg(): void {
+        $this->resetAfterTest();
+
+        $course = $this->getDataGenerator()->create_course();
+        $generator = $this->getDataGenerator()->get_plugin_generator('mod_assign');
+        $user = $this->getDataGenerator()->create_and_enrol($course);
+
+        $assign = $this->create_instance($course, [
+            'assignsubmission_file_enabled' => 1,
+            'assignsubmission_file_maxfiles' => 1,
+            'assignsubmission_file_maxsizebytes' => 1024 * 1024,
+        ]);
+        $fileplugin = $assign->get_plugin_by_type('assignsubmission', 'file');
+        $generator->create_submission([
+            'userid' => $user->id,
+            'cmid' => $assign->get_course_module()->id,
+            'file' => 'mod/assign/feedback/editpdf/tests/fixtures/heic.jpg',
+        ]);
+        $submission = $assign->get_user_submission($user->id, false);
+        $files = $fileplugin->get_files($submission, $user);
+        $this->assertEquals('image/jpeg', $files['/heic.jpg']->get_mimetype());
+
+        // Invoke the save_jpg_to_pdf method expecting there to be no exceptions.
+        $method = new \ReflectionMethod('\assignfeedback_editpdf\document_services', 'save_jpg_to_pdf');
+        $retfile = $method->invoke(null, $assign, $user->id, 1, $files['/heic.jpg']);
+        $this->assertNull($retfile);
+        $this->assertDebuggingCalled("Could not convert {$files['/heic.jpg']->get_contenthash()} jpg to pdf: " .
+            "TCPDF ERROR: [Image] Unable to get the size of the image: ", DEBUG_ALL);
+    }
+
     /**
      * Test that get_combined_document_for_attempt() method rotates the image only once.
      */