[3.6] bpo-31393: Fix the use of PyUnicode_READY(). (GH-3451). (#3453)

(cherry picked from commit e3b2b4b8d9e751b49e3550cb83ba39b54fdc377c)

1 files changed, 10 insertions, 7 deletions

diff --git a/Python/ceval.c b/Python/ceval.c
index 4aa3250cd0..2b74d0e573 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -5307,13 +5307,16 @@ import_all_from(PyObject *locals, PyObject *v)
                 PyErr_Clear();
             break;
         }
-        if (skip_leading_underscores &&
-            PyUnicode_Check(name) &&
-            PyUnicode_READY(name) != -1 &&
-            PyUnicode_READ_CHAR(name, 0) == '_')
-        {
-            Py_DECREF(name);
-            continue;
+        if (skip_leading_underscores && PyUnicode_Check(name)) {
+            if (PyUnicode_READY(name) == -1) {
+                Py_DECREF(name);
+                err = -1;
+                break;
+            }
+            if (PyUnicode_READ_CHAR(name, 0) == '_') {
+                Py_DECREF(name);
+                continue;
+            }
         }
         value = PyObject_GetAttr(v, name);
         if (value == NULL)