Re: [PATCH] vfio/igd: Fix potential overflow in igd_gtt_memory_size()

[Alex Williamson]

On Tue,  7 Jan 2025 14:06:04 +0100
Cédric Le Goater <clg@redhat.com> wrote:

> The risk is mainly theoretical since the applied bit mask will keep
> the 'ggms' shift value below 3. Nevertheless, let's use a 64 bit
> integer type and resolve the coverity issue.
> 
> Resolves: Coverity CID 1585908
> Fixes: 1e1eac5f3dcd ("vfio/igd: canonicalize memory size calculations")
> Signed-off-by: Cédric Le Goater <clg@redhat.com>
> ---
>  hw/vfio/igd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
> index 
> 0740a5dd8cc9346a92c4613194faa8dea42e1d98..b5303ea565d6a344d0a43273f288bbb4a7f48327
>  100644
> --- a/hw/vfio/igd.c
> +++ b/hw/vfio/igd.c
> @@ -133,7 +133,7 @@ static uint64_t igd_gtt_memory_size(int gen, uint16_t 
> gmch)
>      } else {
>          ggms = (gmch >> IGD_GMCH_GEN8_GGMS_SHIFT) & IGD_GMCH_GEN8_GGMS_MASK;
>          if (ggms != 0) {
> -            ggms = 1 << ggms;
> +            ggms = 1ULL << ggms;
>          }
>      }
>  

Reviewed-by: Alex Williamson <alex.williamson@redhat.com>