Re: [PATCH v2 10/13] vtpmmgr: Remove bogus cast from TPM2_GetRandom

["Daniel P. Smith" <dpsmith.dev@xxxxxxxxx>]

On 5/6/21 9:59 AM, Jason Andryuk wrote:
> The UINT32 <-> UINT16 casting in TPM2_GetRandom is incorrect.  Use a
> local UINT16 as needed for the TPM hardware command and assign the
> result.
> 
> Suggested-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
> Signed-off-by: Jason Andryuk <jandryuk@xxxxxxxxx>
> ---

Reviewed-by: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>

>  stubdom/vtpmmgr/tpm2.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/stubdom/vtpmmgr/tpm2.c b/stubdom/vtpmmgr/tpm2.c
> index 655e6d164c..ebd06eac74 100644
> --- a/stubdom/vtpmmgr/tpm2.c
> +++ b/stubdom/vtpmmgr/tpm2.c
> @@ -427,15 +427,22 @@ abort_egress:
>  
>  TPM_RC TPM2_GetRandom(UINT32 * bytesRequested, BYTE * randomBytes)
>  {
> +    UINT16 bytesReq;
>      TPM_BEGIN(TPM_ST_NO_SESSIONS, TPM_CC_GetRandom);
>  
> -    ptr = pack_UINT16(ptr, (UINT16)*bytesRequested);
> +    if (*bytesRequested > UINT16_MAX)
> +        bytesReq = UINT16_MAX;
> +    else
> +        bytesReq = *bytesRequested;
> +
> +    ptr = pack_UINT16(ptr, bytesReq);
>  
>      TPM_TRANSMIT();
>      TPM_UNPACK_VERIFY();
>  
> -    ptr = unpack_UINT16(ptr, (UINT16 *)bytesRequested);
> -    ptr = unpack_TPM_BUFFER(ptr, randomBytes, *bytesRequested);
> +    ptr = unpack_UINT16(ptr, &bytesReq);
> +    *bytesRequested = bytesReq;
> +    ptr = unpack_TPM_BUFFER(ptr, randomBytes, bytesReq);
>  
>  abort_egress:
>      return status;
>