python: check return value of Python object functions (RHBZ#1406906)

Verify the returned values of Python Object constructor functions
are not NULL before adding them to a collection.

This is particularly relevant when constructing Unicode strings in
Python 3 as they will return NULL if non UTF-8 characters are present.

Signed-off-by: Matteo Cafasso <noxdafox@gmail.com>

generator/python.ml

@@ -155,12 +155,20 @@ and generate_python_structs () =
     pr "PyObject *\n";
     pr "guestfs_int_py_put_%s_list (struct guestfs_%s_list *%ss)\n" typ typ typ;
     pr "{\n";
-    pr "  PyObject *list;\n";
+    pr "  PyObject *list, *element;\n";
     pr "  size_t i;\n";
     pr "\n";
     pr "  list = PyList_New (%ss->len);\n" typ;
-    pr "  for (i = 0; i < %ss->len; ++i)\n" typ;
-    pr "    PyList_SetItem (list, i, guestfs_int_py_put_%s (&%ss->val[i]));\n" typ typ;
+    pr "  if (list == NULL)\n";
+    pr "    return NULL;\n";
+    pr "  for (i = 0; i < %ss->len; ++i) {\n" typ;
+    pr "    element = guestfs_int_py_put_%s (&%ss->val[i]);\n" typ typ;
+    pr "    if (element == NULL) {\n";
+    pr "      Py_CLEAR (list);\n";
+    pr "      return NULL;\n";
+    pr "    }\n";
+    pr "    PyList_SetItem (list, i, element);\n";
+    pr "  }\n";
     pr "  return list;\n";
     pr "};\n";
     pr "#endif\n";
@@ -174,54 +182,72 @@ and generate_python_structs () =
       pr "PyObject *\n";
       pr "guestfs_int_py_put_%s (struct guestfs_%s *%s)\n" typ typ typ;
       pr "{\n";
-      pr "  PyObject *dict;\n";
+      pr "  PyObject *dict, *value;\n";
       pr "\n";
       pr "  dict = PyDict_New ();\n";
+      pr "  if (dict == NULL)\n";
+      pr "    return NULL;\n";
       List.iter (
         function
         | name, FString ->
-            pr "  PyDict_SetItemString (dict, \"%s\",\n" name;
-            pr "                        guestfs_int_py_fromstring (%s->%s));\n"
-              typ name
+            pr "  value = guestfs_int_py_fromstring (%s->%s);" typ name;
+            pr "  if (value == NULL)\n";
+            pr "    goto err;\n";
+            pr "  PyDict_SetItemString (dict, \"%s\", value);\n" name;
         | name, FBuffer ->
-            pr "  PyDict_SetItemString (dict, \"%s\",\n" name;
-            pr "                        guestfs_int_py_fromstringsize (%s->%s, %s->%s_len));\n"
-              typ name typ name
+            pr "  value = guestfs_int_py_fromstringsize (%s->%s, %s->%s_len);\n"
+              typ name typ name;
+            pr "  if (value == NULL)\n";
+            pr "    goto err;\n";
+            pr "  PyDict_SetItemString (dict, \"%s\", value);\n" name;
         | name, FUUID ->
-            pr "  PyDict_SetItemString (dict, \"%s\",\n" name;
-            pr "                        guestfs_int_py_fromstringsize (%s->%s, 32));\n"
-              typ name
-        | name, (FBytes|FUInt64) ->
-            pr "  PyDict_SetItemString (dict, \"%s\",\n" name;
-            pr "                        PyLong_FromUnsignedLongLong (%s->%s));\n"
-              typ name
-        | name, FInt64 ->
-            pr "  PyDict_SetItemString (dict, \"%s\",\n" name;
-            pr "                        PyLong_FromLongLong (%s->%s));\n"
-              typ name
-        | name, FUInt32 ->
-            pr "  PyDict_SetItemString (dict, \"%s\",\n" name;
-            pr "                        PyLong_FromUnsignedLong (%s->%s));\n"
-              typ name
-        | name, FInt32 ->
-            pr "  PyDict_SetItemString (dict, \"%s\",\n" name;
-            pr "                        PyLong_FromLong (%s->%s));\n"
-              typ name
-        | name, FOptPercent ->
-            pr "  if (%s->%s >= 0)\n" typ name;
-            pr "    PyDict_SetItemString (dict, \"%s\",\n" name;
-            pr "                          PyFloat_FromDouble ((double) %s->%s));\n"
+            pr "  value = guestfs_int_py_fromstringsize (%s->%s, 32);\n"
               typ name;
+            pr "  if (value == NULL)\n";
+            pr "    goto err;\n";
+            pr "  PyDict_SetItemString (dict, \"%s\", value);\n" name;
+        | name, (FBytes|FUInt64) ->
+            pr "  value = PyLong_FromUnsignedLongLong (%s->%s);\n" typ name;
+            pr "  if (value == NULL)\n";
+            pr "    goto err;\n";
+            pr "  PyDict_SetItemString (dict, \"%s\", value);\n" name;
+        | name, FInt64 ->
+            pr "  value = PyLong_FromLongLong (%s->%s);\n" typ name;
+            pr "  if (value == NULL)\n";
+            pr "    goto err;\n";
+            pr "  PyDict_SetItemString (dict, \"%s\", value);\n" name;
+        | name, FUInt32 ->
+            pr "  value = PyLong_FromUnsignedLong (%s->%s);\n" typ name;
+            pr "  if (value == NULL)\n";
+            pr "    goto err;\n";
+            pr "  PyDict_SetItemString (dict, \"%s\", value);\n" name;
+        | name, FInt32 ->
+            pr "  value = PyLong_FromLong (%s->%s);\n" typ name;
+            pr "  if (value == NULL)\n";
+            pr "    goto err;\n";
+            pr "  PyDict_SetItemString (dict, \"%s\", value);\n" name;
+        | name, FOptPercent ->
+            pr "  if (%s->%s >= 0) {\n" typ name;
+            pr "    value = PyFloat_FromDouble ((double) %s->%s);\n" typ name;
+            pr "    if (value == NULL)\n";
+            pr "      goto err;\n";
+            pr "    PyDict_SetItemString (dict, \"%s\", value);\n" name;
+            pr "  }\n";
             pr "  else {\n";
             pr "    Py_INCREF (Py_None);\n";
             pr "    PyDict_SetItemString (dict, \"%s\", Py_None);\n" name;
             pr "  }\n"
         | name, FChar ->
-            pr "  PyDict_SetItemString (dict, \"%s\",\n" name;
-            pr "                        guestfs_int_py_fromstringsize (&%s->%s, 1));\n"
-              typ name
+            pr "  value = guestfs_int_py_fromstringsize (&%s->%s, 1);\n"
+              typ name;
+            pr "  if (value == NULL)\n";
+            pr "    goto err;\n";
+            pr "  PyDict_SetItemString (dict, \"%s\", value);\n" name;
       ) cols;
       pr "  return dict;\n";
+      pr " err:\n";
+      pr "  Py_CLEAR (dict);\n";
+      pr "  return NULL;\n";
       pr "};\n";
       pr "#endif\n";
       pr "\n";
@@ -472,16 +498,20 @@ and generate_python_actions actions () =
            pr "  if (py_r == NULL) goto out;\n";
        | RStringList _ ->
            pr "  py_r = guestfs_int_py_put_string_list (r);\n";
-           pr "  guestfs_int_free_string_list (r);\n"
+           pr "  guestfs_int_free_string_list (r);\n";
+           pr "  if (py_r == NULL) goto out;\n";
        | RStruct (_, typ) ->
            pr "  py_r = guestfs_int_py_put_%s (r);\n" typ;
-           pr "  guestfs_free_%s (r);\n" typ
+           pr "  guestfs_free_%s (r);\n" typ;
+           pr "  if (py_r == NULL) goto out;\n";
        | RStructList (_, typ) ->
            pr "  py_r = guestfs_int_py_put_%s_list (r);\n" typ;
-           pr "  guestfs_free_%s_list (r);\n" typ
+           pr "  guestfs_free_%s_list (r);\n" typ;
+           pr "  if (py_r == NULL) goto out;\n";
        | RHashtable _ ->
            pr "  py_r = guestfs_int_py_put_table (r);\n";
-           pr "  guestfs_int_free_string_list (r);\n"
+           pr "  guestfs_int_free_string_list (r);\n";
+           pr "  if (py_r == NULL) goto out;\n";
        | RBufferOut _ ->
            pr "  py_r = guestfs_int_py_fromstringsize (r, size);\n";
            pr "  free (r);\n";

python/handle.c

@@ -324,15 +324,23 @@ guestfs_int_py_get_string_list (PyObject *obj)
 PyObject *
 guestfs_int_py_put_string_list (char * const * const argv)
 {
-  PyObject *list;
+  PyObject *list, *item;
   size_t argc, i;
 
   for (argc = 0; argv[argc] != NULL; ++argc)
     ;
 
   list = PyList_New (argc);
+  if (list == NULL)
+    return NULL;
   for (i = 0; i < argc; ++i) {
-    PyList_SetItem (list, i, guestfs_int_py_fromstring (argv[i]));
+    item = guestfs_int_py_fromstring (argv[i]);
+    if (item == NULL) {
+      Py_CLEAR (list);
+      return NULL;
+    }
+
+    PyList_SetItem (list, i, item);
   }
 
   return list;
@@ -341,21 +349,35 @@ guestfs_int_py_put_string_list (char * const * const argv)
 PyObject *
 guestfs_int_py_put_table (char * const * const argv)
 {
-  PyObject *list, *item;
+  PyObject *list, *tuple, *item;
   size_t argc, i;
 
   for (argc = 0; argv[argc] != NULL; ++argc)
     ;
 
   list = PyList_New (argc >> 1);
+  if (list == NULL)
+    return NULL;
   for (i = 0; i < argc; i += 2) {
-    item = PyTuple_New (2);
-    PyTuple_SetItem (item, 0, guestfs_int_py_fromstring (argv[i]));
-    PyTuple_SetItem (item, 1, guestfs_int_py_fromstring (argv[i+1]));
-    PyList_SetItem (list, i >> 1, item);
+    tuple = PyTuple_New (2);
+    if (tuple == NULL)
+      goto err;
+    item = guestfs_int_py_fromstring (argv[i]);
+    if (item == NULL)
+      goto err;
+    PyTuple_SetItem (tuple, 0, item);
+    item = guestfs_int_py_fromstring (argv[i+1]);
+    if (item == NULL)
+      goto err;
+    PyTuple_SetItem (tuple, 1, item);
+    PyList_SetItem (list, i >> 1, tuple);
   }
 
   return list;
+ err:
+  Py_CLEAR (list);
+  Py_CLEAR (tuple);
+  return NULL;
 }
 
 PyObject *

python/t/test830RHBZ1406906.py

@@ -0,0 +1,57 @@
+# libguestfs Python bindings
+# Copyright (C) 2017 Red Hat Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+import os
+import sys
+import shutil
+import tempfile
+import unittest
+
+import guestfs
+
+
+class Test830RHBZ1406906(unittest.TestCase):
+    def setUp(self):
+        self.tempdir = tempfile.mkdtemp()
+
+    def tearDown(self):
+        shutil.rmtree(self.tempdir)
+
+    def test_rhbz1406906(self):
+        g = guestfs.GuestFS(python_return_dict=True)
+
+        g.add_drive_scratch(512 * 1024 * 1024)
+        g.launch()
+
+        g.part_disk("/dev/sda", "mbr")
+        g.mkfs("ext4", "/dev/sda1")
+        g.mount("/dev/sda1", "/")
+
+        self.assertEqual(g.find("/"), ['lost+found'])
+
+        # touch file with illegal unicode character
+        non_utf8_fname = "\udcd4"
+        open(os.path.join(self.tempdir, non_utf8_fname), "w").close()
+
+        g.copy_in(self.tempdir, "/")
+
+        if sys.version_info >= (3, 0):
+            with self.assertRaises(UnicodeDecodeError):
+                g.find("/")  # segfault here on Python 3
+        elif sys.version_info >= (2, 0):
+            self.assertTrue(
+                any(path for path in g.find("/") if non_utf8_fname in path))