NPE on "return" bytecode of java.net.NetworkInterface

[David M. Lloyd]

On 11/14/2016 11:02 AM, David M. Lloyd wrote:
> On 11/14/2016 09:54 AM, David M. Lloyd wrote:
>> On 11/14/2016 09:39 AM, Chris Hegarty wrote:
>>>
>>> On 14/11/16 15:29, Andrew Haley wrote:
>>>> On 14/11/16 14:47, David M. Lloyd wrote:
>>>>
>>>>> Since this method is called from a native method, is it possible
>>>>> that somehow the native method is generating an NPE, but the Java
>>>>> method is still in the stack context?  I assume that what is
>>>>> happening here is some kind of class init order snafu, but it's
>>>>> pretty tricky to diagnose exactly with this non-intuitive stack.
>>>>
>>>> java.net.NetworkInterface.getAll() will return null if it fails to
>>>> create an instance of NetworkInterface.  It's quite possible that
>>>> inlining will make it appear that a NPE at getAll's caller is reported
>>>> at the return.
>>>>
>>>> Try either TieredStopAtLevel=1 or disable compilation for getAll().
>>>
>>> Additionally, is it possible to run with '-Xcheck:jni' ?
>>
>> We'll give it a shot.
>
> We're having a hard time getting JVM arguments set in all the processes
> of the test suite; we're working on that, but in the mean time, some
> more possibly related problems came up (and maybe this is starting to
> move into a hotspot-dev category?)...
>
> Now we're seeing NPEs originating at odd places, like one of these three
> instructions:
>
>        0: aload_0
>        1: invokestatic  #10                 // Method
> doInject:(Lorg/jboss/msc/service/ValueInjection;)V
>        4: return
>
> None of which should possibly be able to trigger an NPE... right? Unless
> it's some kind of unexpected SIGSEGV that looks sufficiently like a null
> dereference...?
>
> So maybe JNI isn't actually a factor.  Or maybe Andrew's inline idea has
> some runway to it.

Here's another:

       87: aload_0
       88: aload         7
       90: putfield      #17                 // Field 
extensionModuleName:Ljava/lang/String;
...
    LocalVariableTable:
       Start  Length  Slot  Name   Signature
           0      94     0  this 
Lorg/jboss/as/controller/extension/ExtensionRegistry$SubsystemRegistrationImpl;

If "this" is null, then something bad is happening, right?

-- 
- DML