snappy-java: Heap buffer overflow in Snappy.uncompress*Array typed-array methods

Impact

Snappy.uncompressCharArray, uncompressShortArray, uncompressIntArray, uncompressLongArray, uncompressFloatArray and uncompressDoubleArray sized the result array by dividing the declared uncompressed byte length by the element size, but native code wrote the full byte length. If the declared length is not a multiple of the element size, up to 7 bytes are written past the end of the Java array, corrupting the heap.

Patches

Fixed in 1.1.10.9 (#739). These methods now reject uncompressed lengths that are not a multiple of the element size with SnappyIOException.

Workarounds

Check that Snappy.uncompressedLength(input) is a multiple of the element size before calling these methods.