Issue #14010: Fix a crash when iterating or deleting deeply nested filters

in itertools module (i.e. itertools.izip(), itertools.chain(), etc).

Lib/test/test_itertools.py

@@ -1413,6 +1413,139 @@ class SubclassWithKwargsTest(unittest.TestCase):
                 self.assertNotIn("does not take keyword arguments", err.args[0])
 
 
+class TestRecursionLimit(unittest.TestCase):
+    # Issue #14010
+    recursionlimit = sys.getrecursionlimit()
+
+    def test_chain(self):
+        it = (0, 1)
+        for _ in xrange(self.recursionlimit):
+            it = chain(it, ())
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+    def test_compress(self):
+        data = (0, 1)
+        selectors = (True, True)
+        it = data
+        for _ in xrange(self.recursionlimit):
+            it = compress(it, selectors)
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+        it = selectors
+        for _ in xrange(self.recursionlimit):
+            it = compress(data, it)
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+    def test_cycle(self):
+        it = (0, 1)
+        for _ in xrange(self.recursionlimit):
+            it = cycle(it)
+        with self.assertRaises(RuntimeError):
+            for _ in range(3):
+                next(it)
+        del it
+
+    def test_dropwhile(self):
+        it = (0, 1, 0)
+        for _ in xrange(self.recursionlimit):
+            it = dropwhile(bool, it)
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+    def test_ifilter(self):
+        it = (0, 1)
+        for _ in xrange(self.recursionlimit):
+            it = ifilter(bool, it)
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+    def test_ifilterfalse(self):
+        it = (0, 1)
+        for _ in xrange(self.recursionlimit):
+            it = ifilterfalse(bool, it)
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+    def test_groupby(self):
+        key = operator.itemgetter(0)
+        it = ((0, []), (1, []))
+        for _ in xrange(self.recursionlimit):
+            it = groupby(it, key)
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+    def test_imap(self):
+        it = (0, 1)
+        for _ in xrange(self.recursionlimit):
+            it = imap(int, it)
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+    def test_islice(self):
+        it = (0, 1)
+        for _ in xrange(self.recursionlimit):
+            it = islice(it, 2)
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+    def test_starmap(self):
+        it = 'ab'
+        for _ in xrange(self.recursionlimit):
+            it = starmap(tuple, it)
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+    def test_takewhile(self):
+        it = (1, 0)
+        for _ in xrange(self.recursionlimit):
+            it = takewhile(bool, it)
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+    def test_izip(self):
+        it = (0, 1)
+        for _ in xrange(self.recursionlimit):
+            it = izip(it)
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+    def test_izip_longest(self):
+        it = (0, 1)
+        for _ in xrange(self.recursionlimit):
+            it = izip_longest(it)
+        with self.assertRaises(RuntimeError):
+            for _ in it:
+                pass
+        del it
+
+
 libreftest = """ Doctest for examples in the library reference: libitertools.tex
 
 
@@ -1645,7 +1778,7 @@ __test__ = {'libreftest' : libreftest}
 def test_main(verbose=None):
     test_classes = (TestBasicOps, TestVariousIteratorArgs, TestGC,
                     RegressionTests, LengthTransparency,
-                    SubclassWithKwargsTest, TestExamples)
+                    SubclassWithKwargsTest, TestExamples, TestRecursionLimit)
     test_support.run_unittest(*test_classes)
 
     # verify reference counting

Misc/NEWS

@@ -11,6 +11,8 @@ Core and Builtins
 
 Library
 -------
+- Issue #14010: Fix a crash when iterating or deleting deeply nested filters
+  in itertools module (i.e. itertools.izip(), itertools.chain(), etc).
 
 - Issue #14254: IDLE now handles readline correctly across shell restarts.
 
@@ -285,7 +287,7 @@ Library
 
 - Issue #12718: Fix interaction with winpdb overriding __import__ by setting
   importer attribute on BaseConfigurator instance.
-  
+
 - Issue #17521: Corrected non-enabling of logger following two calls to
   fileConfig().
 

Modules/itertoolsmodule.c

@@ -54,12 +54,14 @@ static void
 groupby_dealloc(groupbyobject *gbo)
 {
     PyObject_GC_UnTrack(gbo);
+    Py_TRASHCAN_SAFE_BEGIN(gbo)
     Py_XDECREF(gbo->it);
     Py_XDECREF(gbo->keyfunc);
     Py_XDECREF(gbo->tgtkey);
     Py_XDECREF(gbo->currkey);
     Py_XDECREF(gbo->currvalue);
     Py_TYPE(gbo)->tp_free(gbo);
+    Py_TRASHCAN_SAFE_END(gbo)
 }
 
 static int
@@ -741,9 +743,11 @@ static void
 cycle_dealloc(cycleobject *lz)
 {
     PyObject_GC_UnTrack(lz);
+    Py_TRASHCAN_SAFE_BEGIN(lz)
     Py_XDECREF(lz->saved);
     Py_XDECREF(lz->it);
     Py_TYPE(lz)->tp_free(lz);
+    Py_TRASHCAN_SAFE_END(lz)
 }
 
 static int
@@ -886,9 +890,11 @@ static void
 dropwhile_dealloc(dropwhileobject *lz)
 {
     PyObject_GC_UnTrack(lz);
+    Py_TRASHCAN_SAFE_BEGIN(lz)
     Py_XDECREF(lz->func);
     Py_XDECREF(lz->it);
     Py_TYPE(lz)->tp_free(lz);
+    Py_TRASHCAN_SAFE_END(lz)
 }
 
 static int
@@ -909,7 +915,10 @@ dropwhile_next(dropwhileobject *lz)
 
     iternext = *Py_TYPE(it)->tp_iternext;
     for (;;) {
+        if (Py_EnterRecursiveCall(" while iterating"))
+            return NULL;
         item = iternext(it);
+        Py_LeaveRecursiveCall();
         if (item == NULL)
             return NULL;
         if (lz->start == 1)
@@ -1030,9 +1039,11 @@ static void
 takewhile_dealloc(takewhileobject *lz)
 {
     PyObject_GC_UnTrack(lz);
+    Py_TRASHCAN_SAFE_BEGIN(lz)
     Py_XDECREF(lz->func);
     Py_XDECREF(lz->it);
     Py_TYPE(lz)->tp_free(lz);
+    Py_TRASHCAN_SAFE_END(lz)
 }
 
 static int
@@ -1053,7 +1064,10 @@ takewhile_next(takewhileobject *lz)
     if (lz->stop == 1)
         return NULL;
 
+    if (Py_EnterRecursiveCall(" while iterating"))
+        return NULL;
     item = (*Py_TYPE(it)->tp_iternext)(it);
+    Py_LeaveRecursiveCall();
     if (item == NULL)
         return NULL;
 
@@ -1221,8 +1235,10 @@ static void
 islice_dealloc(isliceobject *lz)
 {
     PyObject_GC_UnTrack(lz);
+    Py_TRASHCAN_SAFE_BEGIN(lz)
     Py_XDECREF(lz->it);
     Py_TYPE(lz)->tp_free(lz);
+    Py_TRASHCAN_SAFE_END(lz)
 }
 
 static int
@@ -1243,7 +1259,10 @@ islice_next(isliceobject *lz)
 
     iternext = *Py_TYPE(it)->tp_iternext;
     while (lz->cnt < lz->next) {
+        if (Py_EnterRecursiveCall(" while iterating"))
+            return NULL;
         item = iternext(it);
+        Py_LeaveRecursiveCall();
         if (item == NULL)
             return NULL;
         Py_DECREF(item);
@@ -1251,7 +1270,10 @@ islice_next(isliceobject *lz)
     }
     if (stop != -1 && lz->cnt >= stop)
         return NULL;
+    if (Py_EnterRecursiveCall(" while iterating"))
+        return NULL;
     item = iternext(it);
+    Py_LeaveRecursiveCall();
     if (item == NULL)
         return NULL;
     lz->cnt++;
@@ -1364,9 +1386,11 @@ static void
 starmap_dealloc(starmapobject *lz)
 {
     PyObject_GC_UnTrack(lz);
+    Py_TRASHCAN_SAFE_BEGIN(lz)
     Py_XDECREF(lz->func);
     Py_XDECREF(lz->it);
     Py_TYPE(lz)->tp_free(lz);
+    Py_TRASHCAN_SAFE_END(lz)
 }
 
 static int
@@ -1384,7 +1408,10 @@ starmap_next(starmapobject *lz)
     PyObject *result;
     PyObject *it = lz->it;
 
+    if (Py_EnterRecursiveCall(" while iterating"))
+        return NULL;
     args = (*Py_TYPE(it)->tp_iternext)(it);
+    Py_LeaveRecursiveCall();
     if (args == NULL)
         return NULL;
     if (!PyTuple_CheckExact(args)) {
@@ -1509,9 +1536,11 @@ static void
 imap_dealloc(imapobject *lz)
 {
     PyObject_GC_UnTrack(lz);
+    Py_TRASHCAN_SAFE_BEGIN(lz)
     Py_XDECREF(lz->iters);
     Py_XDECREF(lz->func);
     Py_TYPE(lz)->tp_free(lz);
+    Py_TRASHCAN_SAFE_END(lz)
 }
 
 static int
@@ -1686,9 +1715,11 @@ static void
 chain_dealloc(chainobject *lz)
 {
     PyObject_GC_UnTrack(lz);
+    Py_TRASHCAN_SAFE_BEGIN(lz)
     Py_XDECREF(lz->active);
     Py_XDECREF(lz->source);
     Py_TYPE(lz)->tp_free(lz);
+    Py_TRASHCAN_SAFE_END(lz)
 }
 
 static int
@@ -2837,9 +2868,11 @@ static void
 compress_dealloc(compressobject *lz)
 {
     PyObject_GC_UnTrack(lz);
+    Py_TRASHCAN_SAFE_BEGIN(lz)
     Py_XDECREF(lz->data);
     Py_XDECREF(lz->selectors);
     Py_TYPE(lz)->tp_free(lz);
+    Py_TRASHCAN_SAFE_END(lz)
 }
 
 static int
@@ -2866,11 +2899,16 @@ compress_next(compressobject *lz)
            exception first).
         */
 
+        if (Py_EnterRecursiveCall(" while iterating"))
+            return NULL;
         datum = datanext(data);
-        if (datum == NULL)
+        if (datum == NULL) {
+            Py_LeaveRecursiveCall();
             return NULL;
+        }
 
         selector = selectornext(selectors);
+        Py_LeaveRecursiveCall();
         if (selector == NULL) {
             Py_DECREF(datum);
             return NULL;
@@ -2983,9 +3021,11 @@ static void
 ifilter_dealloc(ifilterobject *lz)
 {
     PyObject_GC_UnTrack(lz);
+    Py_TRASHCAN_SAFE_BEGIN(lz)
     Py_XDECREF(lz->func);
     Py_XDECREF(lz->it);
     Py_TYPE(lz)->tp_free(lz);
+    Py_TRASHCAN_SAFE_END(lz)
 }
 
 static int
@@ -3006,7 +3046,10 @@ ifilter_next(ifilterobject *lz)
 
     iternext = *Py_TYPE(it)->tp_iternext;
     for (;;) {
+        if (Py_EnterRecursiveCall(" while iterating"))
+            return NULL;
         item = iternext(it);
+        Py_LeaveRecursiveCall();
         if (item == NULL)
             return NULL;
 
@@ -3128,9 +3171,11 @@ static void
 ifilterfalse_dealloc(ifilterfalseobject *lz)
 {
     PyObject_GC_UnTrack(lz);
+    Py_TRASHCAN_SAFE_BEGIN(lz)
     Py_XDECREF(lz->func);
     Py_XDECREF(lz->it);
     Py_TYPE(lz)->tp_free(lz);
+    Py_TRASHCAN_SAFE_END(lz)
 }
 
 static int
@@ -3151,7 +3196,10 @@ ifilterfalse_next(ifilterfalseobject *lz)
 
     iternext = *Py_TYPE(it)->tp_iternext;
     for (;;) {
+        if (Py_EnterRecursiveCall(" while iterating"))
+            return NULL;
         item = iternext(it);
+        Py_LeaveRecursiveCall();
         if (item == NULL)
             return NULL;
 
@@ -3551,9 +3599,11 @@ static void
 izip_dealloc(izipobject *lz)
 {
     PyObject_GC_UnTrack(lz);
+    Py_TRASHCAN_SAFE_BEGIN(lz)
     Py_XDECREF(lz->ittuple);
     Py_XDECREF(lz->result);
     Py_TYPE(lz)->tp_free(lz);
+    Py_TRASHCAN_SAFE_END(lz)
 }
 
 static int
@@ -3576,15 +3626,15 @@ izip_next(izipobject *lz)
 
     if (tuplesize == 0)
         return NULL;
+    if (Py_EnterRecursiveCall(" while iterating"))
+        return NULL;
     if (Py_REFCNT(result) == 1) {
         Py_INCREF(result);
         for (i=0 ; i < tuplesize ; i++) {
             it = PyTuple_GET_ITEM(lz->ittuple, i);
             item = (*Py_TYPE(it)->tp_iternext)(it);
-            if (item == NULL) {
-                Py_DECREF(result);
-                return NULL;
-            }
+            if (item == NULL)
+                goto error;
             olditem = PyTuple_GET_ITEM(result, i);
             PyTuple_SET_ITEM(result, i, item);
             Py_DECREF(olditem);
@@ -3592,18 +3642,21 @@ izip_next(izipobject *lz)
     } else {
         result = PyTuple_New(tuplesize);
         if (result == NULL)
-            return NULL;
+            goto error;
         for (i=0 ; i < tuplesize ; i++) {
             it = PyTuple_GET_ITEM(lz->ittuple, i);
             item = (*Py_TYPE(it)->tp_iternext)(it);
-            if (item == NULL) {
-                Py_DECREF(result);
-                return NULL;
-            }
+            if (item == NULL)
+                goto error;
             PyTuple_SET_ITEM(result, i, item);
         }
     }
+    Py_LeaveRecursiveCall();
     return result;
+error:
+    Py_XDECREF(result);
+    Py_LeaveRecursiveCall();
+    return NULL;
 }
 
 PyDoc_STRVAR(izip_doc,
@@ -3892,10 +3945,12 @@ static void
 izip_longest_dealloc(iziplongestobject *lz)
 {
     PyObject_GC_UnTrack(lz);
+    Py_TRASHCAN_SAFE_BEGIN(lz)
     Py_XDECREF(lz->ittuple);
     Py_XDECREF(lz->result);
     Py_XDECREF(lz->fillvalue);
     Py_TYPE(lz)->tp_free(lz);
+    Py_TRASHCAN_SAFE_END(lz)
 }
 
 static int

Objects/abstract.c

@@ -3104,7 +3104,10 @@ PyObject *
 PyIter_Next(PyObject *iter)
 {
     PyObject *result;
+    if (Py_EnterRecursiveCall(" while iterating"))
+        return NULL;
     result = (*iter->ob_type->tp_iternext)(iter);
+    Py_LeaveRecursiveCall();
     if (result == NULL &&
         PyErr_Occurred() &&
         PyErr_ExceptionMatches(PyExc_StopIteration))