Re: [PATCH] MdeModulePkg/DxeCore: base code protection on permission attributes

["Yao, Jiewen" <jiewen.yao@intel.com>]

Hi Ard
I agree with you on this enhancement.

I prefer to adding the description as comment in the code, so that people can get clear picture when he/she reads the code.

//
// Instead of assuming that a PE/COFF section of type EFI_IMAGE_SCN_CNT_CODE
// can always be mapped read-only, classify a section as a code section only
// if it has the executable attribute set and the writable attribute cleared.
//
// This adheres more closely to the PE/COFF spec, and avoids issues with
// Linux OS loaders that consists of a single read/write/execute section.
//
if ((Section[Index].Characteristics & (EFI_IMAGE_SCN_MEM_WRITE | EFI_IMAGE_SCN_MEM_EXECUTE)) == EFI_IMAGE_SCN_MEM_EXECUTE) {

With comment update, reviewed-by: Jiewen.yao@intel.com

Thank you
Yao Jiewen


> -----Original Message-----
> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
> Sent: Saturday, February 25, 2017 1:51 AM
> To: edk2-devel@lists.01.org; Yao, Jiewen <jiewen.yao@intel.com>
> Cc: Gao, Liming <liming.gao@intel.com>; Ard Biesheuvel
> <ard.biesheuvel@linaro.org>
> Subject: [PATCH] MdeModulePkg/DxeCore: base code protection on permission
> attributes
>
> Instead of assuming that a PE/COFF section of type EFI_IMAGE_SCN_CNT_CODE
> can always be mapped read-only, classify a section as a code section only
> if it has the executable attribute set and the writable attribute cleared.
>
> This adheres more closely to the PE/COFF spec, and avoids issues with
> Linux OS loaders that consists of a single read/write/execute section.
>
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
> b/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
> index 1142dcc5a83d..3e037607a6be 100644
> --- a/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
> +++ b/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
> @@ -533,7 +533,7 @@ ProtectUefiImageCommon (
>        Name[7]
>        ));
>
> -    if ((Section[Index].Characteristics & EFI_IMAGE_SCN_CNT_CODE) != 0) {
> +    if ((Section[Index].Characteristics & (EFI_IMAGE_SCN_MEM_WRITE |
> EFI_IMAGE_SCN_MEM_EXECUTE)) == EFI_IMAGE_SCN_MEM_EXECUTE) {
>        DEBUG ((DEBUG_VERBOSE, "  VirtualSize          - 0x%08x\n",
> Section[Index].Misc.VirtualSize));
>        DEBUG ((DEBUG_VERBOSE, "  VirtualAddress       - 0x%08x\n",
> Section[Index].VirtualAddress));
>        DEBUG ((DEBUG_VERBOSE, "  SizeOfRawData        - 0x%08x\n",
> Section[Index].SizeOfRawData));
> --
> 2.7.4