RFR: 8284910: Buffer clean in PasswordCallback [v2]

[Sean Mullan]

On Mon, 18 Apr 2022 15:21:18 GMT, Xue-Lei Andrew Fan <xuelei at openjdk.org> wrote:

>> Please review this password cleanup enhancement in the PasswordCallback implementation.  This is one of the effort to clean up the buffered passwords.
>> 
>> The PasswordCallback.setPassword() clones the password, but is not registered for cleanup. An application could call clearPassword() for the purpose, but it would be nice to cleanup the buffer as well if clearPassword() was not called in an application. And, if the setPassword() get called multiple times, the clearPassword() should also be called the same times if not relying on finalization. It could be fragile in practice.
>
> Xue-Lei Andrew Fan has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update test case

I am not quite seeing the rationale for this change. Are you trying to protect against callers forgetting to call `clearPassword`? Is that really our responsibility? Even if so, then @stuart-marks suggestion about clearing interim passwords is relevant and this solution seems incomplete. But I think trying to fix that will necessitate some specification changes and also possibly some added implementation complexity to detect if code has or has not called `clearPassword`.

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PR: https://git.openjdk.java.net/jdk/pull/8272