Re: [edk2-platforms][PATCH V1 1/1] IntelSiliconPkg/IntelVTdDxe: Fix NULL pointer dereference

["Ni, Ray" <ray.ni@intel.com>]

Michael,


> -----Original Message-----
> From: Kubacki, Michael A
> Sent: Friday, August 23, 2019 7:54 PM
> To: devel@edk2.groups.io
> Cc: Ni, Ray <ray.ni@intel.com>; Chaganty, Rangasai V <rangasai.v.chaganty@intel.com>
> Subject: [edk2-platforms][PATCH V1 1/1] IntelSiliconPkg/IntelVTdDxe: Fix NULL pointer dereference
> 
> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2116
> 
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Rangasai V Chaganty <rangasai.v.chaganty@intel.com>
> Signed-off-by: Michael Kubacki <michael.a.kubacki@intel.com>
> ---
>  Silicon/Intel/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)
> 
> diff --git a/Silicon/Intel/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
> b/Silicon/Intel/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
> index 956ebb2d3d..9b6135ef94 100644
> --- a/Silicon/Intel/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
> +++ b/Silicon/Intel/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
> @@ -158,10 +158,13 @@ ProcessRequestedAccessAttribute (
>  }
> 
>  /**
> -  return the UEFI memory information.
> +  Return UEFI memory map information.
> +
> +  @param[out] Below4GMemoryLimit  The below 4GiB memory limit address or 0 if insufficient resources exist to
> +                                  determine the address.
> +  @param[out] Above4GMemoryLimit  The above 4GiB memory limit address or 0 if insufficient resources exist to
> +                                  determine the address.
> 
> -  @param[out] Below4GMemoryLimit  The below 4GiB memory limit
> -  @param[out] Above4GMemoryLimit  The above 4GiB memory limit
>  **/
>  VOID
>  ReturnUefiMemoryMap (
> @@ -206,7 +209,11 @@ ReturnUefiMemoryMap (
>      // we process bogus entries and create bogus E820 entries.
>      //
>      EfiMemoryMap = (EFI_MEMORY_DESCRIPTOR *) AllocatePool (EfiMemoryMapSize);
> -    ASSERT (EfiMemoryMap != NULL);
> +    if (EfiMemoryMap == NULL) {
> +      ASSERT (EfiMemoryMap != NULL);

Above line may trigger a unreachable code error from some static code scanner.
How about move assertion to the line before if?

> +      return;
> +    }
> +
>      Status = gBS->GetMemoryMap (
>                      &EfiMemoryMapSize,
>                      EfiMemoryMap,
> @@ -218,7 +225,6 @@ ReturnUefiMemoryMap (
>        FreePool (EfiMemoryMap);
>      }
>    } while (Status == EFI_BUFFER_TOO_SMALL);
> -
>    ASSERT_EFI_ERROR (Status);
> 
>    //
> @@ -242,9 +248,6 @@ ReturnUefiMemoryMap (
>      NextEfiEntry  = NEXT_MEMORY_DESCRIPTOR (EfiEntry, EfiDescriptorSize);
>    }
> 
> -  //
> -  //
> -  //
>    DEBUG ((DEBUG_INFO, "MemoryMap:\n"));
>    EfiEntry        = EfiMemoryMap;
>    EfiMemoryMapEnd = (EFI_MEMORY_DESCRIPTOR *) ((UINT8 *) EfiMemoryMap + EfiMemoryMapSize);
> --
> 2.16.2.windows.1