Re: [edk2-devel] [PATCH 1/2] MdeModulePkg/Bus/Ata/AtaAtapiPassThru: Fix SIGN_EXTENSION Coverity issue

["Ard Biesheuvel" <ardb@kernel.org>]

On Fri, 2 Jun 2023 at 21:42, Ranbir Singh <rsingh@ventanamicro.com> wrote:
>
> From: Ranbir Singh <Ranbir.Singh3@Dell.com>
>
> Line number 1348 does contain a typecast with UINT32, but it is after
> all the operations (16-bit left shift followed by OR'ing) are over.
> To avoid any SIGN_EXTENSION, typecast the intermediate result after
> 16-bit left shift operation immediately with UINT32.
>

What is wrong with sign extension?

> Cc: Hao A Wu <hao.a.wu@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4204
> Signed-off-by: Ranbir Singh <Ranbir.Singh3@Dell.com>
> ---
>  MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c b/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c
> index 50406fe0270d..70c4ca27dc68 100644
> --- a/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c
> +++ b/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c
> @@ -1345,7 +1345,7 @@ AtaPassThruPassThru (
>      // Check logical block size
>      //
>      if ((IdentifyData->AtaData.phy_logic_sector_support & BIT12) != 0) {
> -      BlockSize = (UINT32)(((IdentifyData->AtaData.logic_sector_size_hi << 16) | IdentifyData->AtaData.logic_sector_size_lo) * sizeof (UINT16));
> +      BlockSize = (((UINT32)(IdentifyData->AtaData.logic_sector_size_hi << 16) | IdentifyData->AtaData.logic_sector_size_lo) * sizeof (UINT16));


The outer parens are now redundant, which means you're assigning
something to BlockSize whose type is based on the type of <something>
* sizeof(UINT16), which is unsigned long not unsigned int, so this
will produce a truncation warning on some compilers.

If you want to suppress the coverity warning without introducing new
ones, better to cast the sizeof() to (UINT32).