Michael Groß created IMAGING-164:
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Summary: Possible dereferencing of possibel null pointer in
IcoImageParser::writeImage
Key: IMAGING-164
URL: https://issues.apache.org/jira/browse/IMAGING-164
Project: Commons Imaging
Issue Type: Bug
Components: Format: ICO
Reporter: Michael Groß
Fix For: Patch Needed
org.apache.commons.imaging.formats.ico.IcoImageParser::writeImage(final
BufferedImage src, final OutputStream os, final ImagingParameters params)
may throw na unexpected NullPointerException because it of the following code:
{noformat}
final SimplePalette palette = paletteFactory.makeExactRgbPaletteSimple(src,
256);
{noformat}
Then asking if the created palette is null. I will discuss where it comes from
below. For now it is interesting that we set the variable bitCount despite the
SimplePalette is null. Currently this makes no sense because the code will
throw a NullPointerException later if SimplePalette is null.
{noformat}
if (palette == null) {
if (hasTransparency) {
bitCount = 32;
} else {
bitCount = 24;
}
{noformat}
In the later for-loop we try to call *getPaletteIndex(rgb)* on the
SimplePalette instance. If it contains null, we'll get a NullPointerException
here.
{noformat}
for (int y = src.getHeight() - 1; y >= 0; y--) {
for (int x = 0; x < src.getWidth(); x++) {
final int argb = src.getRGB(x, y);
if (bitCount < 8) {
final int rgb = 0xffffff & argb;
final int index = palette.getPaletteIndex(rgb); // possible
NullPointerException
...
} else if (bitCount == 8) {
final int rgb = 0xffffff & argb;
final int index = palette.getPaletteIndex(rgb); //
possible NullPointerException
{noformat}
Why can SimplePalette be null? It comes from
PaletteFactory::makeExactRgbPaletteSimple(final BufferedImage src, final int
max). As it's javadoc says it will "fails by returning {@code null} if there
are more than {@code max} colors necessary":
{noformat}
if (rgbs.add(rgb) && rgbs.size() > max) {
return null;
}
{noformat}
My first idea goes to throw a RunTimeException rather than returning null. But
one has to check if there are cases where the return of null causes some error
handlich i.e. increasing the number of colors or creating another object.
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