static BOOL zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, wStream* stream, size_t segmentSize)
{
	BYTE c;
	BYTE flags;
	UINT32 extra = 0;
	int opIndex;
	int haveBits;
	int inPrefix;
 	UINT32 count;
 	UINT32 distance;
 	BYTE* pbSegment;
	size_t cbSegment;
 
	if (!zgfx || !stream)
		return FALSE;

	cbSegment = segmentSize - 1;

	if ((Stream_GetRemainingLength(stream) < segmentSize) || (segmentSize < 1) ||
	    (segmentSize > UINT32_MAX))
 		return FALSE;
 
 	Stream_Read_UINT8(stream, flags); /* header (1 byte) */
	zgfx->OutputCount = 0;
	pbSegment = Stream_Pointer(stream);
	Stream_Seek(stream, cbSegment);

 	if (!(flags & PACKET_COMPRESSED))
 	{
 		zgfx_history_buffer_ring_write(zgfx, pbSegment, cbSegment);

		if (cbSegment > sizeof(zgfx->OutputBuffer))
			return FALSE;

 		CopyMemory(zgfx->OutputBuffer, pbSegment, cbSegment);
 		zgfx->OutputCount = cbSegment;
 		return TRUE;
	}

	zgfx->pbInputCurrent = pbSegment;
	zgfx->pbInputEnd = &pbSegment[cbSegment - 1];
	/* NumberOfBitsToDecode = ((NumberOfBytesToDecode - 1) * 8) - ValueOfLastByte */
	zgfx->cBitsRemaining = 8 * (cbSegment - 1) - *zgfx->pbInputEnd;
	zgfx->cBitsCurrent = 0;
	zgfx->BitsCurrent = 0;

	while (zgfx->cBitsRemaining)
	{
		haveBits = 0;
		inPrefix = 0;

		for (opIndex = 0; ZGFX_TOKEN_TABLE[opIndex].prefixLength != 0; opIndex++)
		{
			while (haveBits < ZGFX_TOKEN_TABLE[opIndex].prefixLength)
			{
				zgfx_GetBits(zgfx, 1);
				inPrefix = (inPrefix << 1) + zgfx->bits;
				haveBits++;
			}

			if (inPrefix == ZGFX_TOKEN_TABLE[opIndex].prefixCode)
			{
				if (ZGFX_TOKEN_TABLE[opIndex].tokenType == 0)
				{
					/* Literal */
					zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
					c = (BYTE)(ZGFX_TOKEN_TABLE[opIndex].valueBase + zgfx->bits);
					zgfx->HistoryBuffer[zgfx->HistoryIndex] = c;

 					if (++zgfx->HistoryIndex == zgfx->HistoryBufferSize)
 						zgfx->HistoryIndex = 0;
 
					if (zgfx->OutputCount >= sizeof(zgfx->OutputBuffer))
						return FALSE;

 					zgfx->OutputBuffer[zgfx->OutputCount++] = c;
 				}
 				else
				{
					zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
					distance = ZGFX_TOKEN_TABLE[opIndex].valueBase + zgfx->bits;

					if (distance != 0)
					{
						/* Match */
						zgfx_GetBits(zgfx, 1);

						if (zgfx->bits == 0)
						{
							count = 3;
						}
						else
						{
							count = 4;
							extra = 2;
							zgfx_GetBits(zgfx, 1);

							while (zgfx->bits == 1)
							{
								count *= 2;
								extra++;
								zgfx_GetBits(zgfx, 1);
							}

							zgfx_GetBits(zgfx, extra);
 							count += zgfx->bits;
 						}
 
						if (count > sizeof(zgfx->OutputBuffer) - zgfx->OutputCount)
							return FALSE;

 						zgfx_history_buffer_ring_read(zgfx, distance, &(zgfx->OutputBuffer[zgfx->OutputCount]), count);
 						zgfx_history_buffer_ring_write(zgfx, &(zgfx->OutputBuffer[zgfx->OutputCount]), count);
 						zgfx->OutputCount += count;
					}
					else
					{
						/* Unencoded */
						zgfx_GetBits(zgfx, 15);
						count = zgfx->bits;
 						zgfx->cBitsRemaining -= zgfx->cBitsCurrent;
 						zgfx->cBitsCurrent = 0;
 						zgfx->BitsCurrent = 0;

						if (count > sizeof(zgfx->OutputBuffer) - zgfx->OutputCount)
							return FALSE;

 						CopyMemory(&(zgfx->OutputBuffer[zgfx->OutputCount]), zgfx->pbInputCurrent, count);
 						zgfx_history_buffer_ring_write(zgfx, zgfx->pbInputCurrent, count);
 						zgfx->pbInputCurrent += count;
						zgfx->cBitsRemaining -= (8 * count);
						zgfx->OutputCount += count;
					}
				}

				break;
			}
		}
	}

	return TRUE;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.