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GH-94262: Don't create frame objects for frames that aren't complete. #94371

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Merged
markshannon merged 11 commits into from
Jul 1, 2022
Merged

GH-94262: Don't create frame objects for frames that aren't complete. #94371

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87e97ae
Add test for creating frame object when making a generator.
markshannon Jun 27, 2022
583d164
Don't expose incomplete frames as frame objects.
markshannon Jun 27, 2022
5043a8b
Add news
markshannon Jun 28, 2022
e81c1f3
Cleanup after test.
markshannon Jun 28, 2022
6d07165
Explain _PyFrame_IsIncomplete()
markshannon Jun 28, 2022
ce0d4b5
Try harder to break things
markshannon Jun 28, 2022
f56451b
Avoid creating frame objects for incomplete frames vai f_back.
markshannon Jun 28, 2022
b69e803
Fix test
markshannon Jun 28, 2022
c648d46
Assert frame is valid when creating frame object.
markshannon Jun 28, 2022
cf0b32c
Prevent test polluting environment
markshannon Jun 28, 2022
939769c
Create all frames on stack from finalizer.
markshannon Jun 29, 2022
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10 changes: 10 additions & 0 deletions Include/internal/pycore_frame.h
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Expand Up @@ -210,6 +210,16 @@ PyGenObject *_PyFrame_GetGenerator(_PyInterpreterFrame *frame)
return (PyGenObject *)(((char *)frame) - offset_in_gen);
}

/* Determine whether a frame is incomplete.
* A frame is incomplete until the first RESUME instruction
* as it may be part way through creating cell objects or a
* generator or coroutine. */
static inline bool
_PyFrame_IsIncomplete(_PyInterpreterFrame *frame)
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{
return frame->prev_instr < _PyCode_CODE(frame->f_code) + frame->f_code->_co_firsttraceable;
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}

#ifdef __cplusplus
}
#endif
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20 changes: 20 additions & 0 deletions Lib/test/test_generators.py
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Expand Up @@ -170,6 +170,26 @@ def f():
g.send(0)
self.assertEqual(next(g), 1)

def test_handle_frame_object_in_creation(self):
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def cb(*args):
try:
sys._getframe(1)
except ValueError:
pass

def gen():
yield 1

thresholds = gc.get_threshold()
gc.callbacks.append(cb)
gc.set_threshold(1, 0, 0)

try:
gen()
finally:
gc.set_threshold(*thresholds)
gc.callbacks.pop()

class ExceptionTest(unittest.TestCase):
# Tests for the issue #23353: check that the currently handled exception
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2022-06-28-10-08-06.gh-issue-94262.m-HWUZ.rst
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@@ -0,0 +1,3 @@
Don't create frame objects for incomplete frames. Prevents the creation of
generators and closures from being observable to Python and C extensions,
restoring the behavior of 3.10 and earlier.
8 changes: 6 additions & 2 deletions Python/frame.c
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Expand Up @@ -68,9 +68,13 @@ take_ownership(PyFrameObject *f, _PyInterpreterFrame *frame)
f->f_frame = frame;
frame->owner = FRAME_OWNED_BY_FRAME_OBJECT;
assert(f->f_back == NULL);
if (frame->previous != NULL) {
_PyInterpreterFrame *prev = frame->previous;
while (prev && _PyFrame_IsIncomplete(prev)) {
prev = prev->previous;
}
if (prev) {
/* Link PyFrameObjects.f_back and remove link through _PyInterpreterFrame.previous */
PyFrameObject *back = _PyFrame_GetFrameObject(frame->previous);
PyFrameObject *back = _PyFrame_GetFrameObject(prev);
if (back == NULL) {
/* Memory error here. */
assert(PyErr_ExceptionMatches(PyExc_MemoryError));
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14 changes: 11 additions & 3 deletions Python/sysmodule.c
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Expand Up @@ -1776,9 +1776,17 @@ sys__getframe_impl(PyObject *module, int depth)
return NULL;
}

while (depth > 0 && frame != NULL) {
frame = frame->previous;
--depth;
if (frame != NULL) {
while (depth > 0) {
frame = frame->previous;
if (frame == NULL) {
break;
}
if (_PyFrame_IsIncomplete(frame)) {
continue;
}
--depth;
}
}
if (frame == NULL) {
_PyErr_SetString(tstate, PyExc_ValueError,
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