IZ96498: JAVA5/6 JIT-INCORRECT REMOVAL OF ARRAY BOUNDS CHECK WHEN USING B YTE OR SHORT INDEX VARIABLE

Subscribe

You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • Error Message: SIGSEGV executing JIT compiled code.
    Other symptoms are possible because of Java heap corruption due
    to this error.
    .
    Stack Trace: N/A
    .
    The problem can only occur when using a byte or short variable
    as the array index and only if the upper limit of the loop is
    larger than can be represented by the variable (e.g. >127 for
    byte or >32767 for short).
    

Local fix

  • The problem can be avoided by using the following Java command
    line option:
    -Xjit:disableLoopVersioner
    Using the above option will degrade performance between 5 and 10
    percent, depending on the application.
    

Problem summary

  • The JIT was removing bound checks when there is a possibility
    that the array index will overflow to a negative value,
    resulting reading or writing to negative offsets.
    

Problem conclusion

  • This defect will be fixed in:
    5.0.0 SR13
    6.0.0 SR10
    .
    The JIT was modified to prevent this problem from occuring.
    .
    To obtain the fix:
    Install build 20110323 or later
    

Temporary fix

Comments

APAR Information

  • APAR number

    IZ96498

  • Reported component name

    JAVA 5 JIT

  • Reported component ID

    620500124

  • Reported release

    500

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-03-10

  • Closed date

    2011-03-22

  • Last modified date

    2011-04-20

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

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

    IZ96499 IZ98871

Fix information

  • Fixed component name

    JAVA 5 JIT

  • Fixed component ID

    620500124

Applicable component levels

  • R500 PSN

       UP



Rate this page:

(0 users)Average rating

Add comments

Document information


More support for:

Runtimes for Java Technology
Just In Time (JIT) Compiler

Software version:

5.0

Reference #:

IZ96498

Modified date:

2011-04-20

Translate my page

Machine Translation

Content navigation