premain: Crash in Infinispan server code caused by NPE under MethodHandleNative::linkDynamicConstant

[Andrew Dinn]

[n.b. resent using correct email id]

A crash due to an NPE was observed in the Infinispan (Data Grid) server 
app when deployed using the Leyden EA. The crash still manifests with 
the latest premain code. The crash happens when an application call 
which employs a method reference as argument enters 
MethodHandleNative::linkDynamicConstant().

         putMakedPasswordImplementations(this::putService, this);

Debugging shows that the call to linkDynamicConstant() returns null.

A simple reproducer for the problem is available as a maven project on 
github:

   https://github.com/tristantarrant/elytron-leyden

The ReadMe provides an explanation of how to reproduce the problem. I 
did so and the debugged to find out some of the details of what is 
happening (see below) but did not fully clarify the problem. Help from 
someone more conversant with the ins and outs of method handle 
bootstraps in premain would be welcome. Details follow.

regards,


Andrew Dinn
-----------

I downloaded the git repo and attached the Java sources using Maven command

   $ mvn dependency:sources

Having manifested the crash by following the instructions in the README 
I reran the leyden JVM under gdb using the following commands to enable 
Java debugging

$ gdb ${LEYDEN_HOME}/bin/java
(gdb) cd /path/to/mvn/project
(gdb) run 
-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005 
-classpath 
/home/adinn/redhat/openjdk/infinispan/elytron-leyden/base/target/elytron-leyden-base-0.0.1-SNAPSHOT.jar:/home/adinn/.m2/repository/org/wildfly/security/wildfly-elytron-credential/2.5.1.Final/wildfly-elytron-credential-2.5.1.Final.jar:/home/adinn/.m2/repository/org/wildfly/security/wildfly-elytron-base/2.5.1.Final/wildfly-elytron-base-2.5.1.Final.jar 
-XX:CacheDataStore=elytron.aot com.redhat.leyden.Main

The problem manifests at WildflyElytronBaseProvider.java:107 in method 
WildflyElytronBaseProvider::putPasswordImplementations() at a call to 
method putMakedPasswordImplementations:

         . . .
         putService(new Service(this, PASSWORD_FACTORY_TYPE, 
"otp-sha384", 
"org.wildfly.security.password.impl.PasswordFactorySpiImpl", emptyList, 
emptyMap));
         putService(new Service(this, PASSWORD_FACTORY_TYPE, 
"otp-sha512", 
"org.wildfly.security.password.impl.PasswordFactorySpiImpl", emptyList, 
emptyMap));
         putMakedPasswordImplementations(this::putService, this); <== 
NPE here
     }

The source code for this method can be found in the following source jar


${M2_REPO}/org/wildfly/security/wildfly-elytron-base/2.5.1.Final/wildfly-elytron-base-2.5.1.Final-sources.jar

(where M2_REPO will normally be ~/.m2/repository)

A step at this point entered MethodHandleNative::linkDynamicConstant 
which in turn entered into ConstantBootstraps.makeConstant(). The caller 
Class at this point is a lambda class which prints as 
org.wildfly.security.WildflyElytronBaseProvider$$Lambda/0x800000000c

Several steps further the code enters BootstrapMethodInvoker::invoke 
(below the app method call but via 3 hidden frames) with bootstrapMethod 
bound to a DirectMethodHandle. After several more steps this enters 
DirectMethodHandle$Holder.invokeStatic which in turn calls 
MethodHandles::classData(Lookup,String,Class).

At this point caller is a MethodHandleLookup for the lambda class 
Lambda/0x800000000c mentioned above. The following call

          Object classdata = classData(caller.lookupClass());

returns null to DirectMethodHandle$Holder.invokeStatic which pops the 
same result back out to BootstrapMethodInvoker::invoke at line 90

                 if (type instanceof Class<?> c) {
                     result = bootstrapMethod.invoke(caller, name, c); 
<== null

This null result pops back out as the value for the call to 
BootstrapMethodInvoker.invoke(), ConstantBootstraps.makeConstant() and 
MethodHandleNative::linkDynamicConstant().