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

This commit is contained in:
Mark Shannon 2022-07-01 11:08:20 +01:00 committed by GitHub
parent 1df9449db2
commit 544531de23
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GPG Key ID: 4AEE18F83AFDEB23
7 changed files with 87 additions and 13 deletions

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@ -134,6 +134,21 @@ _PyFrame_SetStackPointer(_PyInterpreterFrame *frame, PyObject **stack_pointer)
frame->stacktop = (int)(stack_pointer - frame->localsplus);
}
/* Determine whether a frame is incomplete.
* A frame is incomplete if it is part way through
* creating cell objects or a generator or coroutine.
*
* Frames on the frame stack are incomplete until the
* first RESUME instruction.
* Frames owned by a generator are always complete.
*/
static inline bool
_PyFrame_IsIncomplete(_PyInterpreterFrame *frame)
{
return frame->owner != FRAME_OWNED_BY_GENERATOR &&
frame->prev_instr < _PyCode_CODE(frame->f_code) + frame->f_code->_co_firsttraceable;
}
/* For use by _PyFrame_GetFrameObject
Do not call directly. */
PyFrameObject *
@ -145,6 +160,8 @@ _PyFrame_MakeAndSetFrameObject(_PyInterpreterFrame *frame);
static inline PyFrameObject *
_PyFrame_GetFrameObject(_PyInterpreterFrame *frame)
{
assert(!_PyFrame_IsIncomplete(frame));
PyFrameObject *res = frame->frame_obj;
if (res != NULL) {
return res;

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@ -170,6 +170,43 @@ class GeneratorTest(unittest.TestCase):
g.send(0)
self.assertEqual(next(g), 1)
def test_handle_frame_object_in_creation(self):
#Attempt to expose partially constructed frames
#See https://github.com/python/cpython/issues/94262
def cb(*args):
inspect.stack()
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 Sneaky:
def __del__(self):
inspect.stack()
sneaky = Sneaky()
sneaky._s = Sneaky()
sneaky._s._s = sneaky
gc.set_threshold(1, 0, 0)
try:
del sneaky
gen()
finally:
gc.set_threshold(*thresholds)
class ExceptionTest(unittest.TestCase):
# Tests for the issue #23353: check that the currently handled exception

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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.

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@ -638,11 +638,10 @@ PyCode_New(int argcount, int kwonlyargcount,
exceptiontable);
}
static const char assert0[4] = {
LOAD_ASSERTION_ERROR,
0,
RAISE_VARARGS,
1
static const char assert0[6] = {
RESUME, 0,
LOAD_ASSERTION_ERROR, 0,
RAISE_VARARGS, 1
};
PyCodeObject *
@ -666,7 +665,7 @@ PyCode_NewEmpty(const char *filename, const char *funcname, int firstlineno)
if (filename_ob == NULL) {
goto failed;
}
code_ob = PyBytes_FromStringAndSize(assert0, 4);
code_ob = PyBytes_FromStringAndSize(assert0, 6);
if (code_ob == NULL) {
goto failed;
}

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@ -1169,8 +1169,14 @@ PyFrame_GetBack(PyFrameObject *frame)
{
assert(frame != NULL);
PyFrameObject *back = frame->f_back;
if (back == NULL && frame->f_frame->previous != NULL) {
back = _PyFrame_GetFrameObject(frame->f_frame->previous);
if (back == NULL) {
_PyInterpreterFrame *prev = frame->f_frame->previous;
while (prev && _PyFrame_IsIncomplete(prev)) {
prev = prev->previous;
}
if (prev) {
back = _PyFrame_GetFrameObject(prev);
}
}
Py_XINCREF(back);
return back;

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@ -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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@ -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,