Re: [edk2-devel] [PATCH] MdePkg: PE loader should zero out dest buffer on allocation

["Laszlo Ersek" <lersek@redhat.com>]

On 01/13/20 09:18, Zhiguang Liu wrote:
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1999
> 
> When PE loader loads image to memory, the first section of image may
> not locate right next to the image header, which causes some memory
> space remaining uninitialized. This is a security issue.
> This patch compares the ending address of image header and the beginning
> address of the first section. If there is a gap, zero out this gap.
> 
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Hao A Wu <hao.a.wu@intel.com>
> Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>
> ---
>  MdePkg/Library/BasePeCoffLib/BasePeCoff.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/MdePkg/Library/BasePeCoffLib/BasePeCoff.c b/MdePkg/Library/BasePeCoffLib/BasePeCoff.c
> index 07bb62f860..2cdfb4a082 100644
> --- a/MdePkg/Library/BasePeCoffLib/BasePeCoff.c
> +++ b/MdePkg/Library/BasePeCoffLib/BasePeCoff.c
> @@ -1306,6 +1306,14 @@ PeCoffLoaderLoadImage (
>    // Load each section of the image
>    //
>    Section = FirstSection;
> +  //
> +  // Zero out the memory space between image header and the first section
> +  //
> +  End  = (CHAR8 *)(ImageContext->ImageAddress + ImageContext->SizeOfHeaders);
> +  Base = PeCoffLoaderImageAddress (ImageContext, Section->VirtualAddress, TeStrippedOffset);
> +  if (End < Base) {
> +    ZeroMem (End, Base - End);
> +  }
>    for (Index = 0; Index < NumberOfSections; Index++) {
>      //
>      // Read the section
> 

CC'ing Marvin

Thanks
Laszlo