bpo-35766 follow-up: Add an error check to new_type_comment() (python#11766)

gvanrossum · web-flow · commit 4b250fc1da9c · 2019-02-11T08:10:42.000-08:00
If PyUnicode_DecodeUTF8() returns NULL, PyArena_AddPyObject() would crash. Found by @msullivan for python/typed_ast#93.
diff --git a/Python/ast.c b/Python/ast.c
@@ -702,6 +702,8 @@ static string
 new_type_comment(const char *s, struct compiling *c)
 {
     PyObject *res = PyUnicode_DecodeUTF8(s, strlen(s), NULL);
+    if (res == NULL)
+        return NULL;
     if (PyArena_AddPyObject(c->c_arena, res) < 0) {
         Py_DECREF(res);
         return NULL;

Original file line number	Diff line number	Diff line change
`@@ -702,6 +702,8 @@ static string`
`702`	`702`	`new_type_comment(const char s, struct compiling c)`
`703`	`703`	`{`
`704`	`704`	`PyObject *res = PyUnicode_DecodeUTF8(s, strlen(s), NULL);`
	`705`	`+ if (res == NULL)`
	`706`	`+ return NULL;`
`705`	`707`	`if (PyArena_AddPyObject(c->c_arena, res) < 0) {`
`706`	`708`	`Py_DECREF(res);`
`707`	`709`	`return NULL;`