gh-144984: Fix crash in ExternalEntityParserCreate() error paths#144992
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raminfp wants to merge 3 commits intopython:mainfrom
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gh-144984: Fix crash in ExternalEntityParserCreate() error paths#144992raminfp wants to merge 3 commits intopython:mainfrom
raminfp wants to merge 3 commits intopython:mainfrom
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When ExternalEntityParserCreate() hits an error path (allocation failure), Py_DECREF(new_parser) triggers xmlparse_dealloc() on a partially-initialized object: 1. handlers is NULL, so clear_handlers dereferences NULL (SEGV). 2. Py_CLEAR(parent) in dealloc already decrements the parent's refcount, so the explicit Py_DECREF(self) is a double-decrement. Fix by adding a NULL guard in clear_handlers and setting parent to NULL before Py_DECREF(new_parser) in each error path so that dealloc does not over-decrement the parent's refcount.
picnixz
reviewed
Feb 19, 2026
picnixz
reviewed
Feb 19, 2026
picnixz
added
needs backport to 3.13
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@hugovk What's our policy about fixing security issues? should we backport them as far as the original security fix went? |
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Fix crash when
ExternalEntityParserCreate()hits an error path(allocation failure).
Py_DECREF(new_parser)callsxmlparse_dealloc()on a partially-initialized object where
handlersis NULL, causing aNULL pointer dereference in
clear_handlers. Additionally,Py_CLEAR(parent)in dealloc already decrements the parent's refcount,making the subsequent
Py_DECREF(self)a double-decrement.clear_handlersparent = NULLbeforePy_DECREF(new_parser)in each error path