Integrated: JDK-8221642: AccessibleObject::setAccessible throws NPE when invoked by JNI code with no java frame on stack

[Mandy Chung]

We considered that option (i.e. default JNI code with no caller frame to 
the unnamed module of the system loader).   It should be very rare for 
such use case.   It's the simplest to keep the same access to public 
members of public classes in packages that are exported unconditionally 
as method invocation and field access as well as java.lang.invoke public 
Lookup.

If a native thread attaching to the VM with no caller wants to break 
encapsulation, it will have to workaround it by calling through a Java 
class.

Mandy

On 1/31/22 9:35 PM, Johannes Kuhn wrote:
> Might be a bit late, but wouldn't it be better to check if the package 
> is exported to at least the unnamed module of the system class loader?
>
> It is currently not possible to add unconditional exports on the 
> command line, but it is possible to add 
> `--add-exports=some.module/some.pkg=ALL-UNNAMED` to the command line.
>
> - Johannes
>
> On 01-Feb-22 1:13, Mandy Chung wrote:
>> On Fri, 28 Jan 2022 17:50:19 GMT, Mandy Chung <mchung at openjdk.org> 
>> wrote:
>>
>>> `AccessibleObject::setAccessible` and `trySetAccessible` methods 
>>> should only allow access to public member of a public type that is 
>>> unconditionally exported consistent with the access check as 
>>> described in the class specification, when invoked by JNI code with 
>>> no Java class on the stack.   The current implementation throws NPE 
>>> when finding the module of the caller class as the caller class is 
>>> null.
>>>
>>> The specification of `canAccess`, `setAccessible` and 
>>> `trySetAccessible` are updated to specify the behavior when the 
>>> caller class is null.   I consider this spec update as a 
>>> clarification as the class specification covers this case.
>>
>> This pull request has now been integrated.
>>
>> Changeset: 9c0104b9
>> Author:    Mandy Chung <mchung at openjdk.org>
>> URL: 
>> https://git.openjdk.java.net/jdk/commit/9c0104b9c96f012da1602f503f641824d78f4260
>> Stats:     193 lines in 3 files changed: 166 ins; 19 del; 8 mod
>>
>> 8221642: AccessibleObject::setAccessible throws NPE when invoked by 
>> JNI code with no java frame on stack
>>
>> Reviewed-by: alanb
>>
>> -------------
>>
>> PR: https://git.openjdk.java.net/jdk/pull/7271