src/java.desktop/share/classes/com/sun/imageio/plugins/gif/GIFImageReader.java

*** 1,7 ****
  /*
!  * Copyright (c) 2000, 2016, 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.  Oracle designates this
--- 1,7 ----
  /*
!  * Copyright (c) 2000, 2020, 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.  Oracle designates this
*** 348,357 ****
--- 348,361 ----
                  } else {
                      int left = blockLength;
                      int off = 0;
                      while (left > 0) {
                          int nbytes = stream.read(block, off, left);
+                         if (nbytes == -1 && left > 0) {
+                             throw new IIOException("Invalid block length for " +
+                                     "LZW encoded image data");
+                         }
                          off += nbytes;
                          left -= nbytes;
                      }
                      nextByte = 0;
                  }
*** 928,937 ****
--- 932,945 ----
              this.blockLength = stream.readUnsignedByte();
              int left = blockLength;
              int off = 0;
              while (left > 0) {
                  int nbytes = stream.read(block, off, left);
+                 if (nbytes == -1 && left > 0) {
+                     throw new IIOException("Invalid block length for " +
+                             "LZW encoded image data");
+                 }
                  left -= nbytes;
                  off += nbytes;
              }
  
              this.bitPos = 0;