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Title: Harden `Unpacker.__init__` re-entry cleanup to prevent buffer/context leaks by Copilot · Pull Request #687 · msgpack/msgpack-python · GitHub

Open Graph Title: Harden `Unpacker.__init__` re-entry cleanup to prevent buffer/context leaks by Copilot · Pull Request #687 · msgpack/msgpack-python

X Title: Harden `Unpacker.__init__` re-entry cleanup to prevent buffer/context leaks by Copilot · Pull Request #687 · msgpack/msgpack-python

Description: Unpacker.__init__ did not safely handle repeated initialization: it replaced self.buf without freeing the previous allocation and reinitialized parser state without clearing in-flight stack objects. This PR makes re-entry cleanup explicit and deterministic. Unpacker lifecycle cleanup Initialize parser context in __cinit__ (unpack_init(&self.ctx)) so cleanup paths always operate on initialized state. On every __init__ entry: clear parse-stack state (unpack_clear(&self.ctx)), reset parser bookkeeping (unpack_init(&self.ctx)), free old internal buffer when present (PyMem_Free(self.buf)), null out the pointer before reallocating (self.buf = NULL). Regression coverage for re-initialization Add a focused unpacker test that drives a mid-parse state (live object held in parse stack), re-calls __init__, and asserts: prior stack-held object is released, parser is reset to empty state, unpacker remains reusable for new input. # __init__ re-entry prologue unpack_clear(&self.ctx) unpack_init(&self.ctx) if self.buf != NULL: PyMem_Free(self.buf) self.buf = NULL Original prompt Create a pull request in repository msgpack/msgpack-python to fix the two Unpacker.__init__ re-initialization bugs described in issue #683. Repository: msgpack/msgpack-python Issue context: Issue #683 reports two related bugs in Unpacker.__init__: Unpacker.__init__ overwrites self.buf via PyMem_Malloc without first freeing the existing buffer, so re-calling __init__ (including subclass super().__init__(...)) leaks the previous allocation. Unpacker.__init__ calls unpack_init rather than clearing existing parser state first, so any live PyObject* references in ctx->stack[1..top] are leaked when re-initializing a mid-stream Unpacker. Requested change: Update the Unpacker.__init__ implementation in the Cython source so that, before allocating a new buffer or reinitializing the unpack context, it safely cleans up any existing state. Specifically, if the instance already has an allocated buffer / active unpack context, clear parser state with unpack_clear(&self.ctx), free the old buffer with PyMem_Free(self.buf), and reset self.buf appropriately before continuing initialization. Requirements: Make the fix in the relevant Cython source file for Unpacker. Ensure the cleanup path is safe for first initialization as well as repeated __init__ calls. Keep the PR focused on these two Unpacker.__init__ bugs only. Regenerate checked-in generated files only if the repository expects that for Cython source changes. Add or update tests if there is an appropriate place to cover re-initialization behavior. Open a pull request that references issue #683 and explains that it fixes both the buffer leak and parse-stack leak on Unpacker.__init__ re-entry. Suggested validation: Run relevant tests for unpacker behavior. If practical, add a regression test covering repeated __init__ calls or subclass reinitialization. The following is the prior conversation context from the user's chat exploration (may be truncated): User: Packer.__getbuffer__ と __releasebuffer__ に @cython.critical_section を追加するPRを作って。 Assistant: PR作成の確認待ちです。GitHub 側の承認が完了したら、その変更で続けて進めます。 User: @copilot Accepted Confirmation: Confirm cloud agent session Assistant: 開始しました。進捗はタスクページで追えます。 User: "Unpacker.init overwrites self.buf via PyMem_Malloc without first freeing" と "Unpacker.init calls unpack_init (not unpack_clear) before re-initializing" を修正するPRを作成して。 Assistant: 確認待ちです。GitHub の承認ダイアログで許可してもらえれば、この PR 作成を続けます。 This pull request was created from Copilot chat.

Open Graph Description: Unpacker.__init__ did not safely handle repeated initialization: it replaced self.buf without freeing the previous allocation and reinitialized parser state without clearing in-flight stack objects...

X Description: Unpacker.__init__ did not safely handle repeated initialization: it replaced self.buf without freeing the previous allocation and reinitialized parser state without clearing in-flight stack objects...

Opengraph URL: https://github.com/msgpack/msgpack-python/pull/687

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