snappy-java's unchecked chunk length leads to DoS

snappy-java is a fast compressor/decompressor for Java. Due to use of an unchecked chunk length, an unrecoverable fatal error can occur in versions prior to 1.1.10.1.

The code in the function hasNextChunk in the fileSnappyInputStream.java checks if a given stream has more chunks to read. It does that by attempting to read 4 bytes. If it wasn’t possible to read the 4 bytes, the function returns false. Otherwise, if 4 bytes were available, the code treats them as the length of the next chunk.

In the case that the compressed variable is null, a byte array is allocated with the size given by the input data. Since the code doesn’t test the legality of the chunkSize variable, it is possible to pass a negative number (such as 0xFFFFFFFF which is -1), which will cause the code to raise a java.lang.NegativeArraySizeException exception. A worse case would happen when passing a huge positive value (such as 0x7FFFFFFF), which would raise the fatal java.lang.OutOfMemoryError error.

Version 1.1.10.1 contains a patch for this issue.