IV95401: ARRAYINDEXOUTOFBOUNDS EXCEPTION IS NOT THROWN

APAR status

• Closed as program error.

Error description

• Error Message: An ArrayIndexOutOfBounds exception is not thrown
  when a negative array index is used which should cause the
  exception to be thrown. Instead the array access will be
  performed which can cause unexpected behaviour and/or a crash.
  .
  Stack Trace: N/A
  .
  This problem can only happen on z Systems. The problem is more
  likely to happen when the Java command line option
  -Xjit:noResumableTrapHandler is used. Note that the -Xrs option
  implies this option.
  

Local fix

Problem summary

• Under certain circumstances, the JIT compiler will generate
  Compare Logical instructions for checking ArrayIndexOutOfBounds
  conditions.  When the JIT compiler determines that the array
  index is a constant value, the bounds check will use an
  instruction with a 16-bit unsigned immediate field to hold the
  index to compare against the array length.  For array lengths
  larger than 2?15, the negative array index values would be
  incorrectly interpreted as valid indices, and no
  ArrayIndexOutOfBoundsExceptions are thrown. If
  -Xjit:noResumableTrapHandler or -Xrs JVM options are used, the
  JIT compiler will generate an instruction with an 8-bit unsigned
  immediate field, resulting in array lengths of larger than 2?7
  to expose the incorrect behaviour.
  

Problem conclusion

• The JIT compiler has been updated to recognize that a negative
  array index will always generate an ArrayIndexOutOfBounds
  exception thus preventing the problem.
  .
  This APAR will be fixed in the following Java Releases:
     8    SR4 FP5   (8.0.4.5)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  Service Refreshes and Fix Packs can be found at:
             https://www.ibm.com/developerworks/java/jdk/
  

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

  JIT

• Fixed component ID

  620700124

Applicable component levels

• R130 PSY

     UP