IV25298: UNREACHABLE BYTECODE BEING WALKED BY THE JIT CAUSES CRASH WHEN B YTECODE IS INVALID.

APAR status

• Closed as program error.

Error description

• Error Message: A SIGSEGV/GPF is received in the JIT compiler
  module (j9jit23.dll/libj9jit23.so). However, the error can also
  manifest itself as improper application behaviour.
  .
  Stack Trace: TR_CFGEdge::TR_CFGEdge
  TR_CFG::addEdge
  TR_CFG::addSuccessorEdges
  TR_CFG::insertBefore
  TR_IlGenerator::walker
  TR_IlGenerator::genExceptionHandlers
  TR_IlGenerator::genILFromByteCodes
  TR_IlGenerator::internalGenIL
  TR_IlGenerator::genIL
  .
  

Local fix

• N/A
  

Problem summary

• The JIT compiler attempted to walk and generate code for
  bytecode only accessible via exception handlers that were
  unreachable. Unreachable bytecodes are not required to pass
  verification. In cases where the unreachable bytecode is
  invalid, the JIT would crash walking the malformed bytecode.
  

Problem conclusion

• This defect will be fixed in:
  5.0.0 SR15
  .
  The JIT bytecode walker now correctly determines the
  reachability of the bytecode in cases when it is only accessible
  via exception handling and does not process incorrect
  unreachable paths.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  JAVA 5 JIT

• Fixed component ID

  620500124

Applicable component levels

• R500 PSY

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