bpo-31243: Fixed PyArg_ParseTuple failure checks. (#3171)

Lib/test/test_io.py

@@ -3253,6 +3253,26 @@ class TextIOWrapperTest(unittest.TestCase):
         t = _make_illegal_wrapper()
         self.assertRaises(TypeError, t.read)
 
+        # Issue 31243: calling read() while the return value of decoder's
+        # getstate() is invalid should neither crash the interpreter nor
+        # raise a SystemError.
+        def _make_very_illegal_wrapper(getstate_ret_val):
+            class BadDecoder:
+                def getstate(self):
+                    return getstate_ret_val
+            def _get_bad_decoder(dummy):
+                return BadDecoder()
+            quopri = codecs.lookup("quopri")
+            with support.swap_attr(quopri, 'incrementaldecoder',
+                                   _get_bad_decoder):
+                return _make_illegal_wrapper()
+        t = _make_very_illegal_wrapper(42)
+        self.assertRaises(TypeError, t.read, 42)
+        t = _make_very_illegal_wrapper(())
+        self.assertRaises(TypeError, t.read, 42)
+        t = _make_very_illegal_wrapper((1, 2))
+        self.assertRaises(TypeError, t.read, 42)
+
     def _check_create_at_shutdown(self, **kwargs):
         # Issue #20037: creating a TextIOWrapper at shutdown
         # shouldn't crash the interpreter.

Misc/NEWS.d/next/Core and Builtins/2017-08-24-13-34-49.bpo-31243.dRJzqR.rst

+Fix a crash in some methods of `io.TextIOWrapper`, when the decoder's state
+is invalid. Patch by Oren Milman.

Modules/_io/textio.c

@@ -1513,15 +1513,23 @@ textiowrapper_read_chunk(textio *self, Py_ssize_t size_hint)
         /* Given this, we know there was a valid snapshot point
          * len(dec_buffer) bytes ago with decoder state (b'', dec_flags).
          */
-        if (PyArg_ParseTuple(state, "OO", &dec_buffer, &dec_flags) < 0) {
+        if (!PyTuple_Check(state)) {
+            PyErr_SetString(PyExc_TypeError,
+                            "illegal decoder state");
+            Py_DECREF(state);
+            return -1;
+        }
+        if (!PyArg_ParseTuple(state,
+                              "OO;illegal decoder state", &dec_buffer, &dec_flags))
+        {
             Py_DECREF(state);
             return -1;
         }
 
         if (!PyBytes_Check(dec_buffer)) {
             PyErr_Format(PyExc_TypeError,
-                         "decoder getstate() should have returned a bytes "
-                         "object, not '%.200s'",
+                         "illegal decoder state: the first item should be a "
+                         "bytes object, not '%.200s'",
                          Py_TYPE(dec_buffer)->tp_name);
             Py_DECREF(state);
             return -1;
@@ -2408,8 +2416,8 @@ _io_TextIOWrapper_tell_impl(textio *self)
         } \
         if (!PyBytes_Check(dec_buffer)) { \
             PyErr_Format(PyExc_TypeError, \
-                         "decoder getstate() should have returned a bytes " \
-                         "object, not '%.200s'", \
+                         "illegal decoder state: the first item should be a " \
+                         "bytes object, not '%.200s'", \
                          Py_TYPE(dec_buffer)->tp_name); \
             Py_DECREF(_state); \
             goto fail; \

Modules/_testcapimodule.c

@@ -864,8 +864,9 @@ test_L_code(PyObject *self)
     PyTuple_SET_ITEM(tuple, 0, num);
 
     value = -1;
-    if (PyArg_ParseTuple(tuple, "L:test_L_code", &value) < 0)
+    if (!PyArg_ParseTuple(tuple, "L:test_L_code", &value)) {
         return NULL;
+    }
     if (value != 42)
         return raiseTestError("test_L_code",
             "L code returned wrong value for long 42");
@@ -878,8 +879,9 @@ test_L_code(PyObject *self)
     PyTuple_SET_ITEM(tuple, 0, num);
 
     value = -1;
-    if (PyArg_ParseTuple(tuple, "L:test_L_code", &value) < 0)
+    if (!PyArg_ParseTuple(tuple, "L:test_L_code", &value)) {
         return NULL;
+    }
     if (value != 42)
         return raiseTestError("test_L_code",
             "L code returned wrong value for int 42");
@@ -1195,8 +1197,9 @@ test_k_code(PyObject *self)
     PyTuple_SET_ITEM(tuple, 0, num);
 
     value = 0;
-    if (PyArg_ParseTuple(tuple, "k:test_k_code", &value) < 0)
+    if (!PyArg_ParseTuple(tuple, "k:test_k_code", &value)) {
         return NULL;
+    }
     if (value != ULONG_MAX)
         return raiseTestError("test_k_code",
             "k code returned wrong value for long 0xFFF...FFF");
@@ -1215,8 +1218,9 @@ test_k_code(PyObject *self)
     PyTuple_SET_ITEM(tuple, 0, num);
 
     value = 0;
-    if (PyArg_ParseTuple(tuple, "k:test_k_code", &value) < 0)
+    if (!PyArg_ParseTuple(tuple, "k:test_k_code", &value)) {
         return NULL;
+    }
     if (value != (unsigned long)-0x42)
         return raiseTestError("test_k_code",
             "k code returned wrong value for long -0xFFF..000042");
@@ -1549,11 +1553,13 @@ test_s_code(PyObject *self)
     /* These two blocks used to raise a TypeError:
      * "argument must be string without null bytes, not str"
      */
-    if (PyArg_ParseTuple(tuple, "s:test_s_code1", &value) < 0)
-    return NULL;
+    if (!PyArg_ParseTuple(tuple, "s:test_s_code1", &value)) {
+        return NULL;
+    }
 
-    if (PyArg_ParseTuple(tuple, "z:test_s_code2", &value) < 0)
-    return NULL;
+    if (!PyArg_ParseTuple(tuple, "z:test_s_code2", &value)) {
+        return NULL;
+    }
 
     Py_DECREF(tuple);
     Py_RETURN_NONE;
@@ -1655,14 +1661,16 @@ test_u_code(PyObject *self)
     PyTuple_SET_ITEM(tuple, 0, obj);
 
     value = 0;
-    if (PyArg_ParseTuple(tuple, "u:test_u_code", &value) < 0)
+    if (!PyArg_ParseTuple(tuple, "u:test_u_code", &value)) {
         return NULL;
+    }
     if (value != PyUnicode_AS_UNICODE(obj))
         return raiseTestError("test_u_code",
             "u code returned wrong value for u'test'");
     value = 0;
-    if (PyArg_ParseTuple(tuple, "u#:test_u_code", &value, &len) < 0)
+    if (!PyArg_ParseTuple(tuple, "u#:test_u_code", &value, &len)) {
         return NULL;
+    }
     if (value != PyUnicode_AS_UNICODE(obj) ||
         len != PyUnicode_GET_SIZE(obj))
         return raiseTestError("test_u_code",
@@ -1694,8 +1702,9 @@ test_Z_code(PyObject *self)
     value2 = PyUnicode_AS_UNICODE(obj);
 
     /* Test Z for both values */
-    if (PyArg_ParseTuple(tuple, "ZZ:test_Z_code", &value1, &value2) < 0)
+    if (!PyArg_ParseTuple(tuple, "ZZ:test_Z_code", &value1, &value2)) {
         return NULL;
+    }
     if (value1 != PyUnicode_AS_UNICODE(obj))
         return raiseTestError("test_Z_code",
             "Z code returned wrong value for 'test'");
@@ -1709,9 +1718,11 @@ test_Z_code(PyObject *self)
     len2 = -1;
 
     /* Test Z# for both values */
-    if (PyArg_ParseTuple(tuple, "Z#Z#:test_Z_code", &value1, &len1,
-                         &value2, &len2) < 0)
+    if (!PyArg_ParseTuple(tuple, "Z#Z#:test_Z_code", &value1, &len1,
+                          &value2, &len2))
+    {
         return NULL;
+    }
     if (value1 != PyUnicode_AS_UNICODE(obj) ||
         len1 != PyUnicode_GET_SIZE(obj))
         return raiseTestError("test_Z_code",
@@ -2033,8 +2044,9 @@ test_empty_argparse(PyObject *self)
     tuple = PyTuple_New(0);
     if (!tuple)
         return NULL;
-    if ((result = PyArg_ParseTuple(tuple, "|:test_empty_argparse")) < 0)
+    if (!(result = PyArg_ParseTuple(tuple, "|:test_empty_argparse"))) {
         goto done;
+    }
     dict = PyDict_New();
     if (!dict)
         goto done;
@@ -2042,8 +2054,9 @@ test_empty_argparse(PyObject *self)
   done:
     Py_DECREF(tuple);
     Py_XDECREF(dict);
-    if (result < 0)
+    if (!result) {
         return NULL;
+    }
     else {
         Py_RETURN_NONE;
     }
@@ -3698,8 +3711,9 @@ test_raise_signal(PyObject* self, PyObject *args)
 {
     int signum, err;
 
-    if (PyArg_ParseTuple(args, "i:raise_signal", &signum) < 0)
+    if (!PyArg_ParseTuple(args, "i:raise_signal", &signum)) {
         return NULL;
+    }
 
     err = raise(signum);
     if (err)