Re: [RFC: PATCH 3/5] Fix Length calculation in PdoQueryId

[Paul Durrant <xadimgnik@xxxxxxxxx>]

On 31/08/2023 08:49, Owen Smith wrote:
> Decrease Length by the string length of the current ID before moving
> the Buffer value to the end of the current ID. Without this, Length
> is not decreased, leading to potential issues with the next call to
> RtlStringCbPrintfW.
>
> Signed-off-by: Owen Smith <owen.smith@xxxxxxxxx>
> ---
>   src/xenvif/pdo.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/src/xenvif/pdo.c b/src/xenvif/pdo.c
> index 1d163c9..d43702e 100644
> --- a/src/xenvif/pdo.c
> +++ b/src/xenvif/pdo.c
> @@ -2100,11 +2100,11 @@ PdoQueryId(
>                                           Revision->Number);
>               ASSERT(NT_SUCCESS(status));
>   
> -            Buffer += wcslen(Buffer);
>               Length -= (ULONG)(wcslen(Buffer) * sizeof (WCHAR));
> +            Buffer += wcslen(Buffer);
This looks fine.

>   
> -            Buffer++;
>               Length -= sizeof (WCHAR);
> +            Buffer++;
This doesn't have any effect AFAICT though. Is it just a cosmetic change 
to keep the updating of 'Buffer' and 'Length' in the same order?
  Paul

>   
>               --Index;
>           }