8190997: PNGImageReader throws NullPointerException when PLTE section is missing

Reviewed-by: serb, bpb, pnarayanan

src/java.desktop/share/classes/com/sun/imageio/plugins/png/PNGImageReader.java

@@ -738,6 +738,17 @@ public class PNGImageReader extends ImageReader {
                 case IDAT_TYPE:
                     // If chunk type is 'IDAT', we've reached the image data.
                     if (imageStartPosition == -1L) {
+                        /*
+                         * The PNG specification mandates that if colorType is
+                         * PNG_COLOR_PALETTE then the PLTE chunk should appear
+                         * before the first IDAT chunk.
+                         */
+                        if (colorType == PNG_COLOR_PALETTE &&
+                            !(metadata.PLTE_present))
+                        {
+                            throw new IIOException("Required PLTE chunk"
+                                    + " missing");
+                        }
                         /*
                          * PNGs may contain multiple IDAT chunks containing
                          * a portion of image data. We store the position of

test/jdk/javax/imageio/plugins/png/PngPLTEChunkMissingTest.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug     8190997
+ * @summary Test verifies that ImageIO.read() throws proper IIOException
+ *          when we have a PNG image with color type PNG_COLOR_PALETTE but
+ *          missing the required PLTE chunk.
+ * @run     main PngPLTEChunkMissingTest
+ */
+
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+import java.util.Base64;
+import javax.imageio.IIOException;
+import javax.imageio.ImageIO;
+
+public class PngPLTEChunkMissingTest {
+
+    // PNG image stream missing the required PLTE chunk
+    private static String inputImageBase64 = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAAB"
+            + "CAMAAAA6fptVAAAACklEQVQYV2P4DwABAQEAWk1v8QAAAABJRU5ErkJgggo=";
+
+    public static void main(String[] args) throws Exception {
+
+        byte[] inputBytes = Base64.getDecoder().decode(inputImageBase64);
+        InputStream in = new ByteArrayInputStream(inputBytes);
+
+        /*
+         * Attempt to read a PNG image of color type PNG_COLOR_PALETTE
+         * but missing the required PLTE chunk.
+         */
+        try {
+            ImageIO.read(in);
+        } catch (IIOException e) {
+            /*
+             * We expect ImageIO to throw IIOException with proper message
+             * instead of throwing NullPointerException.
+             */
+            Throwable cause = e.getCause();
+            if (cause == null ||
+                (!(cause.getMessage().
+                 equals("Required PLTE chunk missing"))))
+            {
+                throw e;
+            }
+        }
+    }
+}
+