APAR status
Closed as program error.
Error description
Error Message: The JVM crashes while accessing a malformed object. Analysis of the crash will show the object came from an array of similarly malformed objects, adjacent to each other and likely overlapping. This problem can only happen on X and Z and with bytecode that was not generated by the Java compiler. . Stack Trace: The stack trace will depend on where the object is accessed from. The problem requires code from non-Java languages and this may be apparent from the call stack. .
Local fix
The problem may be avoided by excluding the method which creates the array from compilation by the JIT. For example if the problem method was a.b.Class1.method1 then the following JVM command line option could be used: -Xjit:exclude={a/b/Class1.method1(*},dontInline={a/b/Class1.meth od1(*} Note that there can only be one Xjit option on the command line, so the above may need to be merged with any existing option that might be in use.
Problem summary
The problem is caused by an optimization in the X and Z code generators for the multianewarray bytecode. In Java this bytecode is only used for arrays of dimension two or higher, but other languages or manually generated bytecodes may use multianewarray for one dimensional arrays. The code generated on X and Z incorrectly assumes a minimum of two dimensions with the potential for malformed objects as a result.
Problem conclusion
The evaluator for multianewarray on X and Z was updated to check the dimensionality of the array before applying the problem optimization. For more detail see https://github.com/eclipse-openj9/openj9/issues/17360 . This APAR will be fixed in the following Releases: . IBM SDK, Java Technology Edition 8 SR8 FP11 (8.0.8.11) . Contact your IBM Product's Service Team for these Service Refreshes and Fix Packs. For those running stand-alone, information about the available maintenance can be found at: https://www.ibm.com/support/pages/java-sdk
Temporary fix
Comments
APAR Information
APAR number
IJ47427
Reported component name
JIT
Reported component ID
620700124
Reported release
270
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2023-07-01
Closed date
2023-07-11
Last modified date
2023-07-11
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
[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSNVBF","label":"Runtimes for Java Technology"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"270","Line of Business":{"code":"LOB36","label":"IBM Automation"}}]
Document Information
Modified date:
12 July 2023