_interpqueuesmodule.c: Use-after-free from dangling items.last pointer
Open
Nobody has claimed this yet.
extension-modules
topic-subinterpreters
type-crash
- Dominant language
- Python
- Stars
- 77.2k
- Forks
- 35.9k
- PR merge metrics
- PR metrics pending
Description
Crash report
What happened?
Summary
_queue_clear_interpreter in Modules/_interpqueuesmodule.c (lines 739-774) never updates queue->items.last when removing the tail item. After the item is freed, items.last is a dangling pointer. Next queue operation writes to freed memory.
I have a working patch on this issue, will sending the PR later.
CPython versions tested on:
CPython main branch
Operating systems tested on:
No response
Output from running 'python -VV' on the command line:
No response
Linked PRs
- gh-146428
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start in Modules/_interpqueuesmodule.c, especially _queue_clear_interpreter around lines 739-774, and review the linked PR gh-146428. Trace queue cleanup and the next queue operation, then verify that the crash path no longer accesses freed queue-item memory.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- c, python
- Domain
- backend
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 25/100