RFR: 8258077: Using -Xcheck:jni can lead to a double-free after JDK-8193234

[Mauro Lacy]

On Fri, 11 Dec 2020 06:45:09 GMT, Mauro Lacy <github.com+11656534+maurolacy at openjdk.org> wrote:

>> I've filed: https://bugs.openjdk.java.net/browse/JDK-8258077
>> 
>> Cheers,
>> David
>
> Hi David,
> 
> Thanks for the issue, I'll change the title to properly reference it.
> 
> The point is that I couldn't find those memory leaks. At least in the openjdk code base, I couldn't find tests for that functionality, so, no memory leaks.
> 
> And, in any case, if there are tests in another code base, they are leaking because they are incorrect (IMO). In that they are not always following the right calling pattern for `ReleasePrimitiveArrayCritical`.
> 
> `ReleasePrimitiveArrayCritical`, despite its name (and to the best of our knowledge), does **not** release the buffer when called with `JNI_COMMIT`. So, it must be called again with a different release mode, to properly release the buffer.
> 
> And this, independently of the JVM flags. Or, it will manifest inconsistent behaviour; which is what's happening.

issue 8258077: Using -Xcheck:jni can lead to a double-free after JDK-8193234

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PR: https://git.openjdk.java.net/jdk/pull/1697