- This PR aims to prevent a buffer overrun issue found in FtwGetLastWriteHeader
function.As per the current code, when there is a malformed blocks (with all bytes as 0s)
then `Offset += FTW_WRITE_TOTAL_SIZE (FtwHeader->NumberOfWrites,
FtwHeader->PrivateDataSize)` would access beyond FtwWorkSpaceSize.
- Also added the signature check to validate work space
Signed-off-by: Sureshkumar Ponnusamy <sponnusamy@microsoft.com>