bpo-37188: Fix a divide-by-zero in arrays of size-0 objects (#13881)

eric-wieser · Stefan Krah · commit 0690c79c419b · 2019-06-07T10:13:26.000+02:00
diff --git a/Lib/ctypes/test/test_arrays.py b/Lib/ctypes/test/test_arrays.py
@@ -208,6 +208,21 @@ class T(Array):
             _type_ = c_int
             _length_ = 0
 
+    def test_empty_element_struct(self):
+        class EmptyStruct(Structure):
+            _fields_ = []
+
+        obj = (EmptyStruct * 2)()  # bpo37188: Floating point exception
+        assert sizeof(obj) == 0
+
+    def test_empty_element_array(self):
+        class EmptyArray(Array):
+            _type_ = c_int
+            _length_ = 0
+
+        obj = (EmptyArray * 2)()  # bpo37188: Floating point exception
+        assert sizeof(obj) == 0
+
     def test_bpo36504_signed_int_overflow(self):
         # The overflow check in PyCArrayType_new() could cause signed integer
         # overflow.
diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
@@ -1518,7 +1518,7 @@ PyCArrayType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
     }
 
     itemsize = itemdict->size;
-    if (length > PY_SSIZE_T_MAX / itemsize) {
+    if (itemsize != 0 && length > PY_SSIZE_T_MAX / itemsize) {
         PyErr_SetString(PyExc_OverflowError,
                         "array too large");
         goto error;

Original file line number	Diff line number	Diff line change
`@@ -1518,7 +1518,7 @@ PyCArrayType_new(PyTypeObject type, PyObject args, PyObject *kwds)`
`1518`	`1518`	`}`
`1519`	`1519`
`1520`	`1520`	`itemsize = itemdict->size;`
`1521`		`- if (length > PY_SSIZE_T_MAX / itemsize) {`
	`1521`	`+ if (itemsize != 0 && length > PY_SSIZE_T_MAX / itemsize) {`
`1522`	`1522`	`PyErr_SetString(PyExc_OverflowError,`
`1523`	`1523`	`"array too large");`
`1524`	`1524`	`goto error;`