Fix SF #762455, segfault when sys.stdout is changed in getattr

nnorwitz · nnorwitz · commit c5131bc256dd · 2003-06-29T14:48:32.000Z
Will backport.
diff --git a/Python/ceval.c b/Python/ceval.c
@@ -1501,6 +1501,11 @@ eval_frame(PyFrameObject *f)
 					err = -1;
 				}
 			}
+			/* PyFile_SoftSpace() can exececute arbitrary code
+			   if sys.stdout is an instance with a __getattr__.
+			   If __getattr__ raises an exception, w will
+			   be freed, so we need to prevent that temporarily. */
+			Py_XINCREF(w);
 			if (w != NULL && PyFile_SoftSpace(w, 0))
 				err = PyFile_WriteString(" ", w);
 			if (err == 0)
@@ -1528,6 +1533,7 @@ eval_frame(PyFrameObject *f)
 			    else
 			    	PyFile_SoftSpace(w, 1);
 			}
+			Py_XDECREF(w);
 			Py_DECREF(v);
 			Py_XDECREF(stream);
 			stream = NULL;

Original file line number	Diff line number	Diff line change
`@@ -1501,6 +1501,11 @@ eval_frame(PyFrameObject *f)`
`1501`	`1501`	`err = -1;`
`1502`	`1502`	`}`
`1503`	`1503`	`}`
	`1504`	`+ /* PyFile_SoftSpace() can exececute arbitrary code`
	`1505`	`+ if sys.stdout is an instance with a __getattr__.`
	`1506`	`+ If __getattr__ raises an exception, w will`
	`1507`	`+ be freed, so we need to prevent that temporarily. */`
	`1508`	`+ Py_XINCREF(w);`
`1504`	`1509`	`if (w != NULL && PyFile_SoftSpace(w, 0))`
`1505`	`1510`	`err = PyFile_WriteString(" ", w);`
`1506`	`1511`	`if (err == 0)`
`@@ -1528,6 +1533,7 @@ eval_frame(PyFrameObject *f)`
`1528`	`1533`	`else`
`1529`	`1534`	`PyFile_SoftSpace(w, 1);`
`1530`	`1535`	`}`
	`1536`	`+ Py_XDECREF(w);`
`1531`	`1537`	`Py_DECREF(v);`
`1532`	`1538`	`Py_XDECREF(stream);`
`1533`	`1539`	`stream = NULL;`