[COMPRESS-363] Overflow in BitInputStream - ASF JIRA

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in Class BitInputStream.java(\src\main\java\org\apache\commons\compress\utils),
funcion:

public long readBits(final int count) throws IOException {
if (count < 0 || count > MAXIMUM_CACHE_SIZE)

{ throw new IllegalArgumentException("count must not be negative or greater than " + MAXIMUM_CACHE_SIZE); }

while (bitsCachedSize < count) {
final long nextByte = in.read();
if (nextByte < 0)

{ return nextByte; }

if (byteOrder == ByteOrder.LITTLE_ENDIAN)

{ bitsCached |= (nextByte << bitsCachedSize); }

else

{ bitsCached <<= 8; bitsCached |= nextByte; }

bitsCachedSize += 8;
}

final long bitsOut;
if (byteOrder == ByteOrder.LITTLE_ENDIAN)

{ bitsOut = (bitsCached & MASKS[count]); bitsCached >>>= count; }

else

{ bitsOut = (bitsCached >> (bitsCachedSize - count)) & MASKS[count]; }

bitsCachedSize -= count;
return bitsOut;
}

I think here "bitsCached |= (nextByte << bitsCachedSize);" will overflow in some cases. for example, below is a test case:

public static void test() {

ByteArrayInputStream in = new ByteArrayInputStream(new byte[]

{87, 45, 66, 15, 90, 29, 88, 61, 33, 74}

);
BitInputStream bin = new BitInputStream(in, ByteOrder.LITTLE_ENDIAN);
try

{ long ret = bin.readBits(5); ret = bin.readBits(63); ret = bin.readBits(12); }

catch (Exception e)

{ e.printStackTrace(); }

}

overflow occur in "bin.readBits(63);" , so ,result in wrong result from "bin.readBits(12);"