Add checks for size overflow on list*n, list+list, tuple+tuple.

Will backport.

Objects/listobject.c

@@ -391,6 +391,8 @@ list_concat(PyListObject *a, PyObject *bb)
 	}
 #define b ((PyListObject *)bb)
 	size = a->ob_size + b->ob_size;
+	if (size < 0)
+		return PyErr_NoMemory();
 	np = (PyListObject *) PyList_New(size);
 	if (np == NULL) {
 		return NULL;
@@ -419,6 +421,8 @@ list_repeat(PyListObject *a, int n)
 	if (n < 0)
 		n = 0;
 	size = a->ob_size * n;
+	if (size/a->ob_size != n)
+		return PyErr_NoMemory();
 	np = (PyListObject *) PyList_New(size);
 	if (np == NULL)
 		return NULL;

Objects/tupleobject.c

@@ -330,6 +330,8 @@ tupleconcat(register PyTupleObject *a, register PyObject *bb)
 	}
 #define b ((PyTupleObject *)bb)
 	size = a->ob_size + b->ob_size;
+	if (size < 0)
+		return PyErr_NoMemory();
 	np = (PyTupleObject *) PyTuple_New(size);
 	if (np == NULL) {
 		return NULL;