Re: [PATCH] MdeModulePkg/NonDiscoverable: fix memory override bug

["Ni, Ruiyu" <ruiyu.ni@intel.com>]

I will wait for Ard's feedback. It's an ARM specific module.

Thanks/Ray

> -----Original Message-----
> From: Zeng, Star
> Sent: Monday, October 30, 2017 6:07 PM
> To: Ni, Ruiyu <ruiyu.ni@intel.com>; Heyi Guo <heyi.guo@linaro.org>; linaro-
> uefi@lists.linaro.org; edk2-devel@lists.01.org
> Cc: Dong, Eric <eric.dong@intel.com>; Ard Biesheuvel
> <ard.biesheuvel@linaro.org>; Zeng, Star <star.zeng@intel.com>
> Subject: RE: [edk2][PATCH] MdeModulePkg/NonDiscoverable: fix memory
> override bug
> 
> Ray,
> Please help take a review to this patch.
> 
> 
> Thanks,
> Star
> -----Original Message-----
> From: Heyi Guo [mailto:heyi.guo@linaro.org]
> Sent: Monday, October 30, 2017 1:48 PM
> To: linaro-uefi@lists.linaro.org; edk2-devel@lists.01.org
> Cc: Heyi Guo <heyi.guo@linaro.org>; Zeng, Star <star.zeng@intel.com>;
> Dong, Eric <eric.dong@intel.com>; Ard Biesheuvel
> <ard.biesheuvel@linaro.org>; Ni, Ruiyu <ruiyu.ni@intel.com>
> Subject: [edk2][PATCH] MdeModulePkg/NonDiscoverable: fix memory
> override bug
> 
> For PciIoPciRead interface, memory prior to Buffer would be written with
> zeros if Offset was larger than sizeof (Dev->ConfigSpace), which would cause
> serious system exception.
> 
> So we add a pre-check branch to avoid memory override.
> 
> Cc: Star Zeng <star.zeng@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Heyi Guo <heyi.guo@linaro.org>
> ---
>  .../Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.c | 5
> +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git
> a/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverable
> PciDeviceIo.c
> b/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverable
> PciDeviceIo.c
> index c836ad6..0e42ae4 100644
> ---
> a/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverable
> PciDeviceIo.c
> +++
> b/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverable
> Pc
> +++ iDeviceIo.c
> @@ -465,6 +465,11 @@ PciIoPciRead (
>    Address = (UINT8 *)&Dev->ConfigSpace + Offset;
>    Length = Count << ((UINTN)Width & 0x3);
> 
> +  if (Offset >= sizeof (Dev->ConfigSpace)) {
> +    ZeroMem (Buffer, Length);
> +    return EFI_SUCCESS;
> +  }
> +
>    if (Offset + Length > sizeof (Dev->ConfigSpace)) {
>      //
>      // Read all zeroes for config space accesses beyond the first
> --
> 1.9.1