BUG: Prevent stackoverflow in conversion to datetime types

Fixes gh-11154

3 files changed, 39 insertions, 10 deletions

diff --git a/numpy/core/include/numpy/npy_3kcompat.h b/numpy/core/include/numpy/npy_3kcompat.h
index 56fbd99af..2d0ccd3b9 100644
--- a/numpy/core/include/numpy/npy_3kcompat.h
+++ b/numpy/core/include/numpy/npy_3kcompat.h
@@ -61,6 +61,14 @@ static NPY_INLINE int PyInt_Check(PyObject *op) {
     PySlice_GetIndicesEx((PySliceObject *)op, nop, start, end, step, slicelength)
 #endif
 
+/* <2.7.11 and <3.4.4 have the wrong argument type for Py_EnterRecursiveCall */
+#if (PY_VERSION_HEX < 0x02070B00) || \
+    ((0x03000000 <= PY_VERSION_HEX) && (PY_VERSION_HEX < 0x03040400))
+    #define Npy_EnterRecursiveCall(x) Py_EnterRecursiveCall((char *)(x))
+#else
+    #define Npy_EnterRecursiveCall(x) Py_EnterRecursiveCall(x)
+#endif
+
 /*
  * PyString -> PyBytes
  */
diff --git a/numpy/core/src/multiarray/datetime.c b/numpy/core/src/multiarray/datetime.c
index b026e5fae..d78eaa042 100644
--- a/numpy/core/src/multiarray/datetime.c
+++ b/numpy/core/src/multiarray/datetime.c
@@ -3718,19 +3718,21 @@ recursive_find_object_datetime64_type(PyObject *obj,
         }
 
         for (i = 0; i < len; ++i) {
+            int ret;
             PyObject *f = PySequence_GetItem(obj, i);
             if (f == NULL) {
                 return -1;
             }
-            if (f == obj) {
-                Py_DECREF(f);
-                return 0;
-            }
-            if (recursive_find_object_datetime64_type(f, meta) < 0) {
+            if (Npy_EnterRecursiveCall(" in recursive_find_object_datetime64_type") != 0) {
                 Py_DECREF(f);
                 return -1;
             }
+            ret = recursive_find_object_datetime64_type(f, meta);
+            Py_LeaveRecursiveCall();
             Py_DECREF(f);
+            if (ret < 0) {
+                return ret;
+            }
         }
 
         return 0;
@@ -3820,19 +3822,21 @@ recursive_find_object_timedelta64_type(PyObject *obj,
         }
 
         for (i = 0; i < len; ++i) {
+            int ret;
             PyObject *f = PySequence_GetItem(obj, i);
             if (f == NULL) {
                 return -1;
             }
-            if (f == obj) {
-                Py_DECREF(f);
-                return 0;
-            }
-            if (recursive_find_object_timedelta64_type(f, meta) < 0) {
+            if (Npy_EnterRecursiveCall(" in recursive_find_object_timedelta64_type") != 0) {
                 Py_DECREF(f);
                 return -1;
             }
+            ret = recursive_find_object_timedelta64_type(f, meta);
+            Py_LeaveRecursiveCall();
             Py_DECREF(f);
+            if (ret < 0) {
+                return ret;
+            }
         }
 
         return 0;
diff --git a/numpy/core/tests/test_datetime.py b/numpy/core/tests/test_datetime.py
index 43e8a3325..ce635d947 100644
--- a/numpy/core/tests/test_datetime.py
+++ b/numpy/core/tests/test_datetime.py
@@ -17,6 +17,11 @@ try:
 except ImportError:
     _has_pytz = False
 
+try:
+    RecursionError
+except NameError:
+    RecursionError = RuntimeError  # python < 3.5
+
 
 class TestDateTime(object):
     def test_datetime_dtype_creation(self):
@@ -1979,6 +1984,18 @@ class TestDateTime(object):
                 continue
             assert_raises(TypeError, np.isnat, np.zeros(10, t))
 
+    def test_corecursive_input(self):
+        # construct a co-recursive list
+        a, b = [], []
+        a.append(b)
+        b.append(a)
+        obj_arr = np.array([None])
+        obj_arr[0] = a
+
+        # gh-11154: This shouldn't cause a C stack overflow
+        assert_raises(RecursionError, obj_arr.astype, 'M8')
+        assert_raises(RecursionError, obj_arr.astype, 'm8')
+
 
 class TestDateTimeData(object):