bpo-36367: Free buffer if realloc fails in tokenize.c (GH-12442) (GH-12470)

(cherry picked from commit cb90c89)

Author: vstinner

Parser/tokenizer.c

@@ -656,9 +656,14 @@ translate_newlines(const char *s, int exec_input, struct tok_state *tok) {
  }
  *current = '\0';
  final_length = current - buf + 1;
- if (final_length < needed_length && final_length)
+ if (final_length < needed_length && final_length) {
  /* should never fail */
- buf = PyMem_REALLOC(buf, final_length);
+ char* result = PyMem_REALLOC(buf, final_length);
+ if (result == NULL) {
+ PyMem_FREE(buf);
+ }
+ buf = result;
+ }
  return buf;
 }
 
@@ -974,6 +979,7 @@ tok_nextc(register struct tok_state *tok)
  newbuf = (char *)PyMem_REALLOC(newbuf,
  newsize);
  if (newbuf == NULL) {
+ PyMem_FREE(tok->buf);
  tok->done = E_NOMEM;
  tok->cur = tok->inp;
  return EOF;