[jira] [Created] (MATH-1149) unsafe initialization in DummyStepInterpolator

["M Kim (JIRA)" <ji...@apache.org>]

M Kim created MATH-1149:
---------------------------

             Summary: unsafe initialization in DummyStepInterpolator
                 Key: MATH-1149
                 URL: https://issues.apache.org/jira/browse/MATH-1149
             Project: Commons Math
          Issue Type: Bug
    Affects Versions: 3.3
            Reporter: M Kim


{code:title=DummyStepInterpolator.java|borderStyle=solid}
  public DummyStepInterpolator(final DummyStepInterpolator interpolator) {
    super(interpolator);
    currentDerivative = interpolator.currentDerivative.clone();
  }
   @Override
  protected StepInterpolator doCopy() {
    return new DummyStepInterpolator(this);
  }
{code}

A constructor in DummyStepInterpolator dereferences a field of the parameter, but a NullPointerException can occur during a call to doCopy().

{code:title=Test.java|borderStyle=solid}
public void test1() throws Throwable {
  DummyStepInterpolator var0 = new DummyStepInterpolator();
  var0.copy();
}
{code}

Here in Test.java, a NPE occurs because copy() calls doCopy() which calls  DummyStepInterpolator(final DummyStepInterpolator) that passes var0 as an argument.

I think this constructor should have a null check for  interpolator.currentDerivative like NordsieckStepInterpolator does.

{code:title=NordsieckStepInterpolator.java|borderStyle=solid}
    public NordsieckStepInterpolator(final NordsieckStepInterpolator interpolator) {
        super(interpolator);
        scalingH      = interpolator.scalingH;
        referenceTime = interpolator.referenceTime;
        if (interpolator.scaled != null) {
            scaled = interpolator.scaled.clone();
        }
        if (interpolator.nordsieck != null) {
            nordsieck = new Array2DRowRealMatrix(interpolator.nordsieck.getDataRef(), true);
        }
        if (interpolator.stateVariation != null) {
            stateVariation = interpolator.stateVariation.clone();
        }
    }

    @Override
    protected StepInterpolator doCopy() {
        return new NordsieckStepInterpolator(this);
    }
{code}




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