scsi: storvsc: Add validation for untrusted Hyper-V values

For additional robustness in the face of Hyper-V errors or malicious
behavior, validate all values that originate from packets that Hyper-V has
sent to the guest. Ensure that invalid values cannot cause data being
copied out of the bounds of the source buffer when calling memcpy. Ensure
that outgoing packets do not have any leftover guest memory that has not
been zeroed out.

Link: https://lore.kernel.org/r/20200706160928.53049-1-lkmlabelt@gmail.com


Cc: James E.J. Bottomley <jejb@linux.ibm.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Andres Beltran <lkmlabelt@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>