[CLOSED] Verify operand stack check about avm

[aionbot]

Comment by JunhanHu-aion (on Wednesday May 09, 2018 at 17:42 GMT)

Can confirm that java.lang.VerifyError will be raised by VM in case of a operand stack overflow.
I'm investigating how to properly use asm library to set the max operand stack size. MethodVisitor.visitMaxs() seems not setting the limit as we intended.

[aionbot]

Comment by jeff-aion (on Wednesday May 09, 2018 at 18:00 GMT)

I believe that is over-ridden by built-in ASM logic, via new ClassWriter(ClassWriter.COMPUTE_FRAMES);
We might need that for things other than operand stack and variable count, though. I think it is also used to compute the stack map, which is probably tricky to do manually.

[aionbot]

Comment by JunhanHu-aion (on Wednesday May 09, 2018 at 21:25 GMT)

Test created as org.aion.avm.core.instrument.BytecodeVerificationTest
Local variable table overflow and Operand stack overflow can be detected by JVM before execution.

[aionbot]

Comment by JunhanHu-aion (on Thursday May 10, 2018 at 15:47 GMT)

Confirmed the loop cases wont break the verifier. Stack map frame can stop the loop from keeping push to the operand stack. Test cases created inside BVT.