do not call into python api if an exception is set (#24022)

Lib/test/test_compile.py

 import math
+import os
 import unittest
 import sys
 import _ast
+import tempfile
 import types
-from test import support
+from test import support, script_helper
 
 class TestSpecifics(unittest.TestCase):
 
@@ -492,6 +494,16 @@ if 1:
         self.assertInvalidSingle('f()\nxy # blah\nblah()')
         self.assertInvalidSingle('x = 5 # comment\nx = 6\n')
 
+    def test_particularly_evil_undecodable(self):
+        # Issue 24022
+        src = b'0000\x00\n00000000000\n\x00\n\x9e\n'
+        with tempfile.TemporaryDirectory() as tmpd:
+            fn = os.path.join(tmpd, "bad.py")
+            with open(fn, "wb") as fp:
+                fp.write(src)
+            res = script_helper.run_python_until_end(fn)[0]
+        self.assertIn(b"Non-UTF-8", res.err)
+
     @support.cpython_only
     def test_compiler_recursion_limit(self):
         # Expected limit is sys.getrecursionlimit() * the scaling factor

Misc/NEWS

@@ -10,6 +10,8 @@ Release date: tba
 Core and Builtins
 -----------------
 
+- Issue #24022: Fix tokenizer crash when processing undecodable source code.
+
 - Issue #23309: Avoid a deadlock at shutdown if a daemon thread is aborted
   while it is holding a lock to a buffered I/O object, and the main thread
   tries to use the same I/O object (typically stdout or stderr).  A fatal

Parser/tokenizer.c

@@ -1301,6 +1301,8 @@ verify_identifier(struct tok_state *tok)
 {
     PyObject *s;
     int result;
+    if (tok->decoding_erred)
+        return 0;
     s = PyUnicode_DecodeUTF8(tok->start, tok->cur - tok->start, NULL);
     if (s == NULL || PyUnicode_READY(s) == -1) {
         if (PyErr_ExceptionMatches(PyExc_UnicodeDecodeError)) {
@@ -1469,11 +1471,8 @@ tok_get(struct tok_state *tok, char **p_start, char **p_end)
             c = tok_nextc(tok);
         }
         tok_backup(tok, c);
-        if (nonascii &&
-            !verify_identifier(tok)) {
-            tok->done = E_IDENTIFIER;
+        if (nonascii && !verify_identifier(tok))
             return ERRORTOKEN;
-        }
         *p_start = tok->start;
         *p_end = tok->cur;
         return NAME;