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GH-93252: Fix error handling for failed Python calls #94693

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merged 4 commits into from
Jul 9, 2022
Merged

GH-93252: Fix error handling for failed Python calls #94693

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d0b41d1
Add failing regression test
brandtbucher Jul 8, 2022
e21751f
Always pop the new frame after a failed call
brandtbucher Jul 8, 2022
eb6f8c4
blurb add
brandtbucher Jul 8, 2022
5b46418
Fix compiler warning
brandtbucher Jul 8, 2022
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12 changes: 12 additions & 0 deletions Lib/test/test_call.py
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,18 @@ def fn(**kw):
self.assertIsInstance(res, dict)
self.assertEqual(list(res.items()), expected)

def test_frames_are_popped_after_failed_calls(self):
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Not that it matters much, but maybe you want to add the CPython specific decorator

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I thought about that, but I figure that this should still pass on any CPython implementation. If you somehow crash here, it's a bug, right? 😉

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Yeah, we have been approaching these kind of tests in different ways so it doesn't matter :)

# GH-93252: stuff blows up if we don't pop the new frame after
# recovering from failed calls:
def f():
pass
for _ in range(1000):
try:
f(None)
except TypeError:
pass
# BOOM!


@cpython_only
class CFunctionCallsErrorMessages(unittest.TestCase):
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2022-07-08-11-44-45.gh-issue-93252.i2358c.rst
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@@ -0,0 +1,2 @@
Fix an issue that caused internal frames to outlive failed Python function
calls, possibly resulting in memory leaks or hard interpreter crashes.
6 changes: 5 additions & 1 deletion Python/ceval.c
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Expand Up @@ -6410,7 +6410,7 @@ _PyEvalFramePushAndInit(PyThreadState *tstate, PyFunctionObject *func,
}
if (initialize_locals(tstate, func, localsarray, args, argcount, kwnames)) {
assert(frame->owner != FRAME_OWNED_BY_GENERATOR);
_PyFrame_Clear(frame);
_PyEvalFrameClearAndPop(tstate, frame);
return NULL;
}
return frame;
Expand All @@ -6432,6 +6432,10 @@ _PyEvalFramePushAndInit(PyThreadState *tstate, PyFunctionObject *func,
static void
_PyEvalFrameClearAndPop(PyThreadState *tstate, _PyInterpreterFrame * frame)
{
// Make sure that this is, indeed, the top frame. We can't check this in
// _PyThreadState_PopFrame, since f_code is already cleared at that point:
assert((PyObject **)frame + frame->f_code->co_framesize ==
tstate->datastack_top);
tstate->recursion_remaining--;
assert(frame->frame_obj == NULL || frame->frame_obj->f_frame == frame);
assert(frame->owner == FRAME_OWNED_BY_THREAD);
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