int __ext4_journal_stop(const char *where, unsigned int line, handle_t *handle)
{
	struct super_block *sb;
	int err;
	int rc;

	if (!ext4_handle_valid(handle)) {
		ext4_put_nojournal(handle);
		return 0;
	}

	if (!handle->h_transaction) {
		err = jbd2_journal_stop(handle);
		return handle->h_err ? handle->h_err : err;
	}

	sb = handle->h_transaction->t_journal->j_private;
	err = handle->h_err;
	rc = jbd2_journal_stop(handle);

	if (!err)
		err = rc;
	if (err)
		__ext4_std_error(sb, where, line, err);
	return err;
}
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.