[3.11] GH-105588: Add missing error checks to some obj2ast_* converters (GH-105839)

GH-105588: Add missing error checks to some obj2ast_* converters (GH-105589) (cherry picked from commit a4056c8) Co-authored-by: Brandt Bucher <brandtbucher@microsoft.com>

Author: miss-islington

Lib/test/test_ast.py

@@ -3,6 +3,7 @@
 import dis
 import enum
 import os
+import re
 import sys
 import types
 import unittest
@@ -862,6 +863,32 @@ def test_null_bytes(self):
  msg="source code string cannot contain null bytes"):
  ast.parse("a\0b")
 
+ def assert_none_check(self, node: type[ast.AST], attr: str, source: str) -> None:
+ with self.subTest(f"{node.__name__}.{attr}"):
+ tree = ast.parse(source)
+ found = 0
+ for child in ast.walk(tree):
+ if isinstance(child, node):
+ setattr(child, attr, None)
+ found += 1
+ self.assertEqual(found, 1)
+ e = re.escape(f"field '{attr}' is required for {node.__name__}")
+ with self.assertRaisesRegex(ValueError, f"^{e}$"):
+ compile(tree, "<test>", "exec")
+
+ def test_none_checks(self) -> None:
+ tests = [
+ (ast.alias, "name", "import spam as SPAM"),
+ (ast.arg, "arg", "def spam(SPAM): spam"),
+ (ast.comprehension, "target", "[spam for SPAM in spam]"),
+ (ast.comprehension, "iter", "[spam for spam in SPAM]"),
+ (ast.keyword, "value", "spam(**SPAM)"),
+ (ast.match_case, "pattern", "match spam:\n case SPAM: spam"),
+ (ast.withitem, "context_expr", "with SPAM: spam"),
+ ]
+ for node, attr, source in tests:
+ self.assert_none_check(node, attr, source)
+
 class ASTHelpers_Test(unittest.TestCase):
  maxDiff = None
 

Misc/NEWS.d/next/Core and Builtins/2023-06-09-11-19-51.gh-issue-105588.Y5ovpY.rst

@@ -0,0 +1,2 @@
+Fix an issue that could result in crashes when compiling malformed
+:mod:`ast` nodes.

Parser/asdl_c.py

@@ -602,6 +602,7 @@ def visitProduct(self, prod, name):
  args = [f.name for f in prod.fields]
  args.extend([a.name for a in prod.attributes])
  self.emit("*out = %s(%s);" % (ast_func_name(name), self.buildArgs(args)), 1)
+ self.emit("if (*out == NULL) goto failed;", 1)
  self.emit("return 0;", 1)
  self.emit("failed:", 0)
  self.emit("Py_XDECREF(tmp);", 1)