Fixed #20411 -- Don't let invalid referers blow up CSRF same origin checks.

Thanks to edevil for the report and saz for the patch.

django/utils/http.py

@@ -226,7 +226,10 @@ def same_origin(url1, url2):
     Checks if two URLs are 'same-origin'
     """
     p1, p2 = urllib_parse.urlparse(url1), urllib_parse.urlparse(url2)
-    return (p1.scheme, p1.hostname, p1.port) == (p2.scheme, p2.hostname, p2.port)
+    try:
+        return (p1.scheme, p1.hostname, p1.port) == (p2.scheme, p2.hostname, p2.port)
+    except ValueError:
+        return False
 
 def is_safe_url(url, host=None):
     """

tests/csrf_tests/tests.py

@@ -283,6 +283,19 @@ class CsrfViewMiddlewareTest(TestCase):
         self.assertNotEqual(None, req2)
         self.assertEqual(403, req2.status_code)
 
+    @override_settings(ALLOWED_HOSTS=['www.example.com'])
+    def test_https_malformed_referer(self):
+        """
+        Test that a POST HTTPS request with a bad referer is rejected
+        """
+        req = self._get_POST_request_with_token()
+        req._is_secure_override = True
+        req.META['HTTP_HOST'] = 'www.example.com'
+        req.META['HTTP_REFERER'] = 'http://http://www.example.com/'
+        req2 = CsrfViewMiddleware().process_view(req, post_form_view, (), {})
+        self.assertNotEqual(None, req2)
+        self.assertEqual(403, req2.status_code)
+
     @override_settings(ALLOWED_HOSTS=['www.example.com'])
     def test_https_good_referer(self):
         """