Re: [edk2-devel] [PATCH] OvmfPkg/PvScsiDxe: Fix VS2019 build error because of implicit cast

["Laszlo Ersek" <lersek@redhat.com>]

On 03/31/20 13:04, Liran Alon wrote:
> Sean reported that VS2019 build produce the following build error:
> INFO - PvScsi.c
> INFO - Generating code
> INFO - d:\a\1\s\OvmfPkg\PvScsiDxe\PvScsi.c(459): error C2220: the following warning is treated as an error
> INFO - d:\a\1\s\OvmfPkg\PvScsiDxe\PvScsi.c(459): warning C4244: '=': conversion from 'const UINT16' to 'UINT8', possible loss of data
> 
> This result from an implicit cast from PVSCSI Response->ScsiStatus
> (Which is UINT16) to Packet->TargetResponse (Which is UINT8).
> 
> Fix this issue by adding an appropriate explicit cast and verify with
> assert that this truncation do not result in loss of data.
> 
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2651
> Reported-by: Sean Brogan <sean.brogan@microsoft.com>
> Signed-off-by: Liran Alon <liran.alon@oracle.com>
> ---
>  OvmfPkg/PvScsiDxe/PvScsi.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/OvmfPkg/PvScsiDxe/PvScsi.c b/OvmfPkg/PvScsiDxe/PvScsi.c
> index 0a66c98421a9..1ca50390c0e5 100644
> --- a/OvmfPkg/PvScsiDxe/PvScsi.c
> +++ b/OvmfPkg/PvScsiDxe/PvScsi.c
> @@ -455,8 +455,12 @@ HandleResponse (
>  
>    //
>    // Report target status
> +  // (Strangely, PVSCSI interface defines Response->ScsiStatus as UINT16.
> +  // But it should de-facto always have a value that fits UINT8. To avoid
> +  // unexpected behavior, verify value is in UINT8 bounds before casting)
>    //
> -  Packet->TargetStatus = Response->ScsiStatus;
> +  ASSERT (Response->ScsiStatus <= MAX_UINT8);
> +  Packet->TargetStatus = (UINT8)Response->ScsiStatus;
>  
>    //
>    // Host adapter status and function return value depend on
> 

Pushed as commit 98936dc4f44b4ef47e7221d435de06a0813aa00a, via
<https://github.com/tianocore/edk2/pull/491>.

Thanks,
Laszlo