Fix segfault when passing empty StringIO/File object to Font

src_c/_freetype.c

@@ -667,6 +667,7 @@ _ftfont_new(PyTypeObject *subtype, PyObject *args, PyObject *kwds)
         obj->bgcolor[1] = 0;
         obj->bgcolor[2] = 0;
         obj->bgcolor[3] = 0;
+        obj->init_generation = current_freetype_generation;
     }
     return (PyObject *)obj;
 }
@@ -783,6 +784,13 @@ _ftfont_init(pgFontObject *self, PyObject *args, PyObject *kwds)
             goto end;
         }
 
+        if (source->size(source) <= 0) {
+            PyErr_Format(PyExc_ValueError,
+                         "Font file object has an invalid file size: %lld",
+                         source->size(source));
+            goto end;
+        }
+
         path = PyObject_GetAttrString(original_file, "name");
         if (!path) {
             PyErr_Clear();
@@ -827,6 +835,13 @@ _ftfont_init(pgFontObject *self, PyObject *args, PyObject *kwds)
         goto end;
     }
 
+    if (source->size(source) <= 0) {
+        PyErr_Format(PyExc_ValueError,
+                     "Font file object has an invalid file size: %lld",
+                     source->size(source));
+        goto end;
+    }
+
     PyObject *path = NULL;
     if (pgRWops_IsFileObject(source)) {
         path = PyObject_GetAttrString(file, "name");
@@ -890,7 +905,6 @@ _ftfont_init(pgFontObject *self, PyObject *args, PyObject *kwds)
     */
     self->freetype = ft;
     ++ft->ref_count;
-    self->init_generation = current_freetype_generation;
 
     rval = 0;
 

src_c/font.c

@@ -1184,6 +1184,13 @@ font_init(PyFontObject *self, PyObject *args, PyObject *kwds)
     if (fontsize <= 1)
         fontsize = 1;
 
+    if (rw->size(rw) <= 0) {
+        PyErr_Format(PyExc_ValueError,
+                     "Font file object has an invalid file size: %lld",
+                     rw->size(rw));
+        goto error;
+    }
+
     Py_BEGIN_ALLOW_THREADS;
     font = TTF_OpenFontRW(rw, 1, fontsize);
     Py_END_ALLOW_THREADS;

test/font_test.py

@@ -2,6 +2,7 @@
 from re import T
 import sys
 import os
+import io
 import unittest
 import pathlib
 import platform
@@ -708,6 +709,12 @@ def test_load_from_file_obj_default(self):
         with open(font_path, "rb") as f:
             font = pygame_font.Font(f)
 
+    def test_load_from_invalid_sized_file_obj(self):
+        pygame.font.init()
+        f = io.StringIO()
+        with self.assertRaises(ValueError):
+            font = pygame.font.Font(f)
+
     def test_load_default_font_filename(self):
         # In font_init, a special case is when the filename argument is
         # identical to the default font file name.

test/freetype_test.py

@@ -1,5 +1,5 @@
 import os
-
+import io
 import unittest
 import ctypes
 import weakref
@@ -158,6 +158,11 @@ def test_freetype_Font_init(self):
         f.__init__(self._bmp_8_75dpi_path, size=12)
         self.assertEqual(f.size, 12.0)
 
+    def test_load_from_invalid_sized_file_obj(self):
+        f = io.StringIO()
+        with self.assertRaises(ValueError):
+            font = f = ft.Font(f, size=24)
+
     @unittest.skipIf(IS_PYPY, "PyPy doesn't use refcounting")
     def test_freetype_Font_dealloc(self):
         import sys
@@ -544,7 +549,9 @@ def test_freetype_Font_name(self):
         f = self._TEST_FONTS["fixed"]
         self.assertEqual(f.name, "Inconsolata")
 
-        self.assertRaises(RuntimeError, lambda: nullfont().name)
+        with self.assertRaises(AttributeError):
+            null_font = ft.Font.__new__(ft.Font)
+            null_font.name
 
     def test_freetype_Font_size(self):
         f = ft.Font(None, size=12)
@@ -1349,7 +1356,10 @@ def test_freetype_Font_resolution(self):
 
     def test_freetype_Font_path(self):
         self.assertEqual(self._TEST_FONTS["sans"].path, self._sans_path)
-        self.assertRaises(pygame.error, lambda: nullfont().path)
+
+        with self.assertRaises(AttributeError):
+            nullfont = ft.Font.__new__(ft.Font)
+            nullfont.path
 
     # This Font cache test is conditional on freetype being built by a debug
     # version of Python or with the C macro PGFT_DEBUG_CACHE defined.