3 files changed, 32 insertions, 15 deletions

diff --git a/Python/_warnings.c b/Python/_warnings.c
index 7c15ce0..4d65bb3 100644
--- a/Python/_warnings.c
+++ b/Python/_warnings.c
@@ -3,7 +3,7 @@
 #include "pycore_interp.h"        // PyInterpreterState.warnings
 #include "pycore_pyerrors.h"
 #include "pycore_pystate.h"       // _PyThreadState_GET()
-#include "frameobject.h"
+#include "frameobject.h"          // PyFrame_GetBack()
 #include "clinic/_warnings.c.h"
 
 #define MODULE_NAME "_warnings"
@@ -815,7 +815,9 @@ static PyFrameObject *
 next_external_frame(PyFrameObject *frame)
 {
     do {
-        frame = frame->f_back;
+        PyFrameObject *back = PyFrame_GetBack(frame);
+        Py_DECREF(frame);
+        frame = back;
     } while (frame != NULL && is_internal_frame(frame));
 
     return frame;
@@ -831,12 +833,15 @@ setup_context(Py_ssize_t stack_level, PyObject **filename, int *lineno,
     PyObject *globals;
 
     /* Setup globals, filename and lineno. */
-    PyFrameObject *f = _PyThreadState_GET()->frame;
+    PyThreadState *tstate = _PyThreadState_GET();
+    PyFrameObject *f = PyThreadState_GetFrame(tstate);
     // Stack level comparisons to Python code is off by one as there is no
     // warnings-related stack level to avoid.
     if (stack_level <= 0 || is_internal_frame(f)) {
         while (--stack_level > 0 && f != NULL) {
-            f = f->f_back;
+            PyFrameObject *back = PyFrame_GetBack(f);
+            Py_DECREF(f);
+            f = back;
         }
     }
     else {
@@ -857,6 +862,7 @@ setup_context(Py_ssize_t stack_level, PyObject **filename, int *lineno,
         Py_DECREF(code);
         Py_INCREF(*filename);
         *lineno = PyFrame_GetLineNumber(f);
+        Py_DECREF(f);
     }
 
     *module = NULL;
@@ -868,7 +874,7 @@ setup_context(Py_ssize_t stack_level, PyObject **filename, int *lineno,
     if (*registry == NULL) {
         int rc;
 
-        if (PyErr_Occurred()) {
+        if (_PyErr_Occurred(tstate)) {
             goto handle_error;
         }
         *registry = PyDict_New();
@@ -887,7 +893,7 @@ setup_context(Py_ssize_t stack_level, PyObject **filename, int *lineno,
     if (*module == Py_None || (*module != NULL && PyUnicode_Check(*module))) {
         Py_INCREF(*module);
     }
-    else if (PyErr_Occurred()) {
+    else if (_PyErr_Occurred(tstate)) {
         goto handle_error;
     }
     else {
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 92ea5e7..914beb7 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -16,7 +16,7 @@ Data members:
 
 #include "Python.h"
 #include "code.h"
-#include "frameobject.h"
+#include "frameobject.h"          // PyFrame_GetBack()
 #include "pycore_ceval.h"         // _Py_RecursionLimitLowerWaterMark()
 #include "pycore_initconfig.h"
 #include "pycore_object.h"
@@ -1787,14 +1787,17 @@ sys__getframe_impl(PyObject *module, int depth)
 /*[clinic end generated code: output=d438776c04d59804 input=c1be8a6464b11ee5]*/
 {
     PyThreadState *tstate = _PyThreadState_GET();
-    PyFrameObject *f = tstate->frame;
+    PyFrameObject *f = PyThreadState_GetFrame(tstate);
 
     if (_PySys_Audit(tstate, "sys._getframe", "O", f) < 0) {
+        Py_DECREF(f);
         return NULL;
     }
 
     while (depth > 0 && f != NULL) {
-        f = f->f_back;
+        PyFrameObject *back = PyFrame_GetBack(f);
+        Py_DECREF(f);
+        f = back;
         --depth;
     }
     if (f == NULL) {
@@ -1802,7 +1805,6 @@ sys__getframe_impl(PyObject *module, int depth)
                          "call stack is not deep enough");
         return NULL;
     }
-    Py_INCREF(f);
     return (PyObject*)f;
 }
 
diff --git a/Python/traceback.c b/Python/traceback.c
index 438a2c4..99b63af 100644
--- a/Python/traceback.c
+++ b/Python/traceback.c
@@ -4,7 +4,7 @@
 #include "Python.h"
 
 #include "code.h"
-#include "frameobject.h"
+#include "frameobject.h"          // PyFrame_GetBack()
 #include "structmember.h"         // PyMemberDef
 #include "osdefs.h"               // SEP
 #ifdef HAVE_FCNTL_H
@@ -798,22 +798,31 @@ dump_traceback(int fd, PyThreadState *tstate, int write_header)
         PUTS(fd, "Stack (most recent call first):\n");
     }
 
-    frame = tstate->frame;
+    frame = PyThreadState_GetFrame(tstate);
     if (frame == NULL) {
         PUTS(fd, "<no Python frame>\n");
         return;
     }
 
     depth = 0;
-    while (frame != NULL) {
+    while (1) {
         if (MAX_FRAME_DEPTH <= depth) {
+            Py_DECREF(frame);
             PUTS(fd, "  ...\n");
             break;
         }
-        if (!PyFrame_Check(frame))
+        if (!PyFrame_Check(frame)) {
+            Py_DECREF(frame);
             break;
+        }
         dump_frame(fd, frame);
-        frame = frame->f_back;
+        PyFrameObject *back = PyFrame_GetBack(frame);
+        Py_DECREF(frame);
+
+        if (back == NULL) {
+            break;
+        }
+        frame = back;
         depth++;
     }
 }