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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Some object-to-AST conversions are missing error checks","articleBody":"The generated code in `Python-ast.c` is missing error checks following the construction of C-level `alias`, `arg`, `comprehension`, `keyword`, `match_item`, and `withitem` nodes from their Python object counterparts. This means it's possible to crash the interpreter by attempting to compile an AST where a required member of these nodes is replaced with `None`:\r\n\r\n```py\r\n\u003e\u003e\u003e import ast\r\n\u003e\u003e\u003e tree = ast.parse(\"\"\"\r\n... match ...:\r\n...     case THIS:\r\n...         ...\r\n... \"\"\")\r\n\u003e\u003e\u003e tree.body[0].cases[0].pattern = None\r\n\u003e\u003e\u003e compile(tree, \"\u003ccrash\u003e\", \"exec\")\r\nSegmentation fault\r\n```\r\n\r\nI'll have a PR up in a minute with the one-line fix.\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-105589\n* gh-105838\n* gh-105839\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/brandtbucher","@type":"Person","name":"brandtbucher"},"datePublished":"2023-06-09T19:01:19.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/105588/cpython/issues/105588"}