GeezerVison is showing github.com — Shim frames can be accessed during frame teardown (via `tstate->cframe->current_frame`) · Issue #100126 · python/cpython
Shim frames can be accessed during frame teardown (via tstate->cframe->current_frame) #100126DescriptionCrash report
In jaraco/jaraco.net#5, I've captured a failure that's emerged as Github updated Python 3.12 from a2 to a3 on Linux. The calling code is using ctypes to call libc functions.
I don't yet have a minimal reproducer. I'm unable to replicate the issue locally as I don't yet have Linux with a3.
- Operating system and architecture: Ubuntu Linux
Linked PRs
Activityillia-v commented on Dec 17, 2022 Tests of urllib3 detected a segmentation fault on 3.12.0a3 too.
https://github.com/urllib3/urllib3/actions/runs/3720502510/jobs/6310016874
Fatal Python error: Segmentation fault on Linux and Windows fatal exception: access violation on Windows happened in one test function.
The function succeeded on macOS, but Fatal Python error: Bus error happened in a different one. illia-v commented on Dec 22, 2022 b72014c is the first commit where the segfault in urllib3's tests happens. AlexWaygood commented on Dec 22, 2022 brandtbucher commented on Dec 22, 2022 I'll look into this too. No promises that I'll have it figured out before the holiday weekend, but it'll be my main priority starting next Tuesday.
Not sure if #99110 is related... hard to tell without a reproducer. illia-v commented on Dec 26, 2022
I'll look into this too. No promises that I'll have it figured out before the holiday weekend, but it'll be my main priority starting next Tuesday.
Thanks!
Not sure if #99110 is related... hard to tell without a reproducer.
It still happens after PR of #99110 is merged. brandtbucher commented on Dec 28, 2022 Here is a reproducer with only pytest:
# pytest crasher.py
import socket
def test_foo():
_ = socket.socket()Indeed, this looks eerily similar to #99729. brandtbucher commented on Dec 28, 2022 Found the issue. PyEval_GetGlobals returns tstate->cframe->current_frame->f_globals. When tearing a frame down, current_frame may be a shim frame. Shim frames have no globals, so the code crashes. brandtbucher commented on Dec 28, 2022 Looks like in general, it is not safe for current_frame to be a shim frame. Too many things can break. brandtbucher commented on Dec 28, 2022 Minimal reproducer, no pytest:
# python crasher.py
import operator
class DelRaises:
def __del__(self):
assert False
def f():
local = DelRaises()
# Call from C, so there is a shim frame above f:
operator.call(f)changed the title [-]Regression in 3.12a3 - segfault in interpreter trampoline[/-] [+]Shim frames can be accessed during frame teardown (via `tstate->cframe->current_frame`)[/+] on Dec 29, 2022brandtbucher commented on Dec 29, 2022 I'm honestly not sure what to do here.
Perhaps, before tearing down a frame, if our previous frame is a shim frame, we should set tstate->cframe to be cframe.previous. But that's adding code to a perf-sensitive path, and it also makes the interaction with INTERPRETER_EXIT awkward, since it tries to do the same thing.
The best option is probably just to add more while (frame && _PyFrame_IsIncomplete(frame)) {frame = frame->previous;} loops to all of the affected areas. It probably makes sense to just add a helper function for this (_PyThreadState_GetInterpreterFrame?), rather than continuing to sprinkle them everywhere.
Thoughts, @markshannon? (I don't think you're out this week... feel free to ignore if so.) brandtbucher commented on Dec 29, 2022 Also going to tag as release-blocker (for now). Yhg1s commented on Jan 9, 2023 @brandtbucher what's the state of this issue (and the attached fix for it)? Should this hold up 3.12.0a4? brandtbucher commented on Jan 9, 2023 Sorry, just got back from vacation and thought it was merged while I was gone. I'm in a meeting right now, but I have one small review comment to apply, then I'll merge.
If it's not too much trouble, I'd like this to make it into the next release. It's not too hard to trigger using frameworks like pytest, so it would be nice to have non-crashy test coverage of the next alpha out in the wild. brandtbucher commented on Jan 9, 2023 Reacted by Illia Volochii
MetadataMetadataStatusShow more project fields
DevelopmentNo branches or pull requestsIssue actions
|