gh-142442: Increase the borrowed ref from faulthandler_get_fileno when file is not None instead of decreasing when it is none

AZero13 · AZero13 · commit 6345ae980b10 · 2025-12-08T18:54:42.000-05:00
Increase the borrowed ref from faulthandler_get_fileno when file is not None instead of decreasing when it is none
diff --git a/Misc/NEWS.d/next/Library/2025-12-08-18-54-22.gh-issue-142442.SFn1RC.rst b/Misc/NEWS.d/next/Library/2025-12-08-18-54-22.gh-issue-142442.SFn1RC.rst
@@ -0,0 +1,3 @@
+Fix faulthandler’s fallback to `sys.stderr` so it owns the reference it
+returns, preventing an accidental decref of `sys.stderr` (or `None`) when no
+file is provided.
diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
@@ -112,9 +112,9 @@ faulthandler_get_fileno(PyObject **file_ptr)
         }
         if (file == Py_None) {
             PyErr_SetString(PyExc_RuntimeError, "sys.stderr is None");
-            Py_DECREF(file);
             return -1;
         }
+        Py_INCREF(file);
     }
     else if (PyLong_Check(file)) {
         if (PyBool_Check(file)) {

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	+Fix faulthandler’s fallback to `sys.stderr` so it owns the reference it
	`2`	+returns, preventing an accidental decref of `sys.stderr` (or `None`) when no
	`3`	`+file is provided.`
Original file line number	Diff line number	Diff line change
`@@ -112,9 +112,9 @@ faulthandler_get_fileno(PyObject **file_ptr)`
`112`	`112`	`}`
`113`	`113`	`if (file == Py_None) {`
`114`	`114`	`PyErr_SetString(PyExc_RuntimeError, "sys.stderr is None");`
`115`		`- Py_DECREF(file);`
`116`	`115`	`return -1;`
`117`	`116`	`}`
	`117`	`+ Py_INCREF(file);`
`118`	`118`	`}`
`119`	`119`	`else if (PyLong_Check(file)) {`
`120`	`120`	`if (PyBool_Check(file)) {`