make the PyUnicode_FSConverter cleanup set the decrefed argument to NULL (closes python#25630)

benjaminp · benjaminp · commit a4d33b34286e · 2015-11-15T21:57:39.000-08:00
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -11,6 +11,9 @@ Release date: TBA
 Core and Builtins
 -----------------
 
+- Issue #25630: Fix a possible segfault during argument parsing in functions
+  that accept filesystem paths.
+
 - Issue #23564: Fixed a partially broken sanity check in the _posixsubprocess
   internals regarding how fds_to_pass were passed to the child.  The bug had
   no actual impact as subprocess.py already avoided it.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
@@ -3614,6 +3614,7 @@ PyUnicode_FSConverter(PyObject* arg, void* addr)
     void *data;
     if (arg == NULL) {
         Py_DECREF(*(PyObject**)addr);
+        *(PyObject**)addr = NULL;
         return 1;
     }
     if (PyBytes_Check(arg)) {

Original file line number	Diff line number	Diff line change
`@@ -3614,6 +3614,7 @@ PyUnicode_FSConverter(PyObject* arg, void* addr)`
`3614`	`3614`	`void *data;`
`3615`	`3615`	`if (arg == NULL) {`
`3616`	`3616`	`Py_DECREF((PyObject*)addr);`
	`3617`	`+ (PyObject*)addr = NULL;`
`3617`	`3618`	`return 1;`
`3618`	`3619`	`}`
`3619`	`3620`	`if (PyBytes_Check(arg)) {`