RFR: 8260009: InstanceKlass::has_as_permitted_subclass() fails if subclass was redefined [v2]

[Harold Seigel]

On Fri, 22 Jan 2021 13:49:40 GMT, Harold Seigel <hseigel at openjdk.org> wrote:

>> Hi Harold,
>> 
>> This makes me wonder whether we can have a similar issue with nestmate checking?
>> 
>> Just curious: is there any way to determine that a Klass k2 is actually a redefinition of Klass k1? I
>> 
>> One nit below, otherwise this seems fine.
>> 
>> Thanks,
>> David
>
> Hi David,
> 
> I agree that this is not an issue for nestmates.  Class redefinition loads the redefined class, and class loading calls verify_member_access(), which does a nestmate check for private access.  But, class loading only calls verify_member_access() for accessing non-private methods, when doing method override checking in check_final_method_override().
> 
> Thanks, Harold
> ________________________________
> From: mlbridge[bot] <notifications at github.com>
> Sent: Thursday, January 21, 2021 5:25 PM
> To: openjdk/jdk <jdk at noreply.github.com>
> Cc: Harold Seigel <harold.seigel at oracle.com>; Mention <mention at noreply.github.com>
> Subject: [External] : Re: [openjdk/jdk] 8260009: InstanceKlass::has_as_permitted_subclass() fails if subclass was redefined (#2184)
> 
> 
> Mailing list message from David Holmes<mailto:david.holmes at oracle.com> on hotspot-dev<mailto:hotspot-dev at openjdk.java.net>:
> 
> On 22/01/2021 8:19 am, David Holmes wrote:
> 
> On Thu, 21 Jan 2021 13:41:44 GMT, Harold Seigel <hseigel at openjdk.org> wrote:
> 
> Please review this fix for JDK-8260009. The fix removes the "if (k2 == k)" check for a valid permitted subclass because the check does not work if "k" is being redefined. It fails because 'k' is a temporary InstanceKlass created when loading the redefined class.
> 
> Instead, the code relies on a name check to determine if 'k' is a permitted subclass.
> 
> The fix was tested with Mach5 tiers 1-2 on Linux, Mac OS, and Windows, tiers 3-5 on Linux x64, and JCK Lang and VM tests.
> 
> Thanks, Harold
> 
> Hi Harold,
> 
> This makes me wonder whether we can have a similar issue with nestmate checking?
> 
> Thinking more, I think not. IIUC the issue here is that the permitted
> subclass check happens as part of redefinition - correct? Whereas there
> is no nestmate access check as part of redefinition.
> 
> David
> 
> —
> You are receiving this because you were mentioned.
> Reply to this email directly, view it on GitHub<https://urldefense.com/v3/__https://github.com/openjdk/jdk/pull/2184*issuecomment-764980526__;Iw!!GqivPVa7Brio!K9lG_bCi-kUDG0EXHNUs42PuDTpuzkrpKpRfThkaBWcD9ct3VwlvM19wzyIVcnwrKA$>, or unsubscribe<https://urldefense.com/v3/__https://github.com/notifications/unsubscribe-auth/AOXZ7OWMVJPHR72ZNL2TXKLS3CSTZANCNFSM4WM4FQFQ__;!!GqivPVa7Brio!K9lG_bCi-kUDG0EXHNUs42PuDTpuzkrpKpRfThkaBWcD9ct3VwlvM19wzyJL1nMdLA$>.

Thanks Lois, Serguei, and David for the reviews!

-------------

PR: https://git.openjdk.java.net/jdk/pull/2184