Re: RFR(xs): 8181419: Race in jdwp invoker handling may lead to crashes or invalid results

[serguei.spit...@oracle.com]

Hi Thomas, The fix looks great to me. Thank you for identifying and fixing the problem! Thanks, Serguei On 6/13/17 06:55, Thomas Stüfe wrote: Ping... Anyone? On Thu, Jun 1, 2017 at 2:18 PM, Thomas Stüfe <thomas.stu...@gmail.com> wrote: Hi all, please take a look at this proposed fix for a theoretical race in the jdwp library. Issue: https://bugs.openjdk.java.net/browse/JDK-8181419 webrev: http://cr.openjdk.java.net/~stuefe/webrevs/8181419-Race-in-jdwp-invoker-handling-may-lead-to-crashes-or-invalid-results/webrev.00/webrev/ In short, this is an addition to Severin's fix to the jdwp invoke handling (https://bugs.openjdk.java.net/browse/JDK-8153711). We have a potential race condition where the delayed cleanup of the saved returnvalue object reference and the exception reference (released in deletePotentiallySavedGlobalRefs() ) may be overtaken by a new request which populates the thread request structure anew. If this happens, deletePotentiallySavedGlobalRefs() may actually release the return value / exception references of the follow up request, if that one was already processed. The solution I choose is safe and conservative. We still release both references, but use the locally saved JNI references. We just avoid accessing the thread local request structure after it has been cleared for reuse. This keeps timing and locking behaviour unchanged. I am currently running jtreg tests for com/sun/jdi on AIX and Linux. Kind Regards, Thomas