IJ24023: JAVA JIT: RARE CRASH READING AN ADDRESS JUST BEYOND THE END OF THE JAVA HEAP

APAR status

• Closed as program error.

Error description

• Error Message: A SIGSEGV is received when executing JIT compiled
  code.
  .
  Stack Trace: {java/util/regex/Pattern$Curly.match} JIT
  {com/myproclassic/server/services/card/PCECardHandlingBean.match
  PatternList} JIT
  {com/myproclassic/server/services/card/PCECardHandlingBean.match
  PatternListWithReplace} JIT
  {com/myproclassic/server/services/card/PCECardHandlingBean.match
  } JIT
  {com/myproclassic/server/services/card/PCECardHandlingBean.getEl
  ementResult} JIT
  This stack trace is one example of the problem. Since the
  problem could potentially occur in other JIT compiled methods,
  any crash in JIT compiled code is a potential example of this
  problem.
  .
  The problem can occur on any platform or OS when using the J9
  JVM, but the problem will be very intermittent because the crash
  will only occur when a specific object is allocated right and
  the end of the Java heap. Therefore the chances of hitting the
  problem is very slim.
  If the address of the illegal access is not just beyond the end
  of the Java heap then this APAR does NOT apply.
  

Local fix

• The problem can be avoid by disable a JIT optimization using the
  following java command line option:
  -Xjit:disableBlockVersioner
  Using this option will have a minor effect on performance, but
  the cost is very likely to be less then 2% in almost all most
  cases.
  

Problem summary

• When attempting to generate an optimized path by removing
  array-bounds-checks the JIT would introduce new upper and lower
  bound checks to insure the optimized path can safely remove the
  array-bounds-checks. In doing so it introduced code that could
  potentially attempt to read passed the end of an object.
  

Problem conclusion

• The JIT was modified so that it will verify the object that it
  is reading from is an instance of the class type we are
  expecting.
  .
  This APAR will be fixed in the following Java Releases:
     8    SR6 FP10  (8.0.6.10)
  .
  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