bpo-42500: Fix recursion in or after except (GH-23568) (#24501)

* Use counter, rather boolean state when handling soft overflows.

(cherry picked from commit 4e7a69bdb63a104587759d7784124492dcdd496e)

1 files changed, 3 insertions, 0 deletions

diff --git a/Python/errors.c b/Python/errors.c
index 87af39d527..d8c2d8b923 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -290,12 +290,14 @@ _PyErr_NormalizeException(PyThreadState *tstate, PyObject **exc,
                           PyObject **val, PyObject **tb)
 {
     int recursion_depth = 0;
+    tstate->recursion_headroom++;
     PyObject *type, *value, *initial_tb;
 
   restart:
     type = *exc;
     if (type == NULL) {
         /* There was no exception, so nothing to do. */
+        tstate->recursion_headroom--;
         return;
     }
 
@@ -347,6 +349,7 @@ _PyErr_NormalizeException(PyThreadState *tstate, PyObject **exc,
     }
     *exc = type;
     *val = value;
+    tstate->recursion_headroom--;
     return;
 
   error: