Re: [edk2-devel] [PATCH v8 1/9] MdeModulePkg: Add new PCD to control the evacuate temporary memory feature (CVE-2019-11098)

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

On 07/24/20 11:54, Guomin Jiang wrote:
> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1614
> 
> The security researcher found that we can get control after NEM disable.
> 
> The reason is that the flash content reside in NEM at startup and the
> code will get the content from flash directly after disable NEM.
> 
> To avoid this vulnerability, the feature will copy the PEIMs from
> temporary memory to permanent memory and only execute the code in
> permanent memory.
> 
> The vulnerability is exist in physical platform and haven't report in
> virtual platform, so the virtual can disable the feature currently.
> 
> When enable the PcdMigrateTemporaryRamFirmwareVolumes, always shadow
> all PEIMs no matter the condition of PcdShadowPeimOnBoot or
> PcdShadowPeimOnS3Boot.
> 
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Hao A Wu <hao.a.wu@intel.com>
> Signed-off-by: Guomin Jiang <guomin.jiang@intel.com>
> ---
>  MdeModulePkg/MdeModulePkg.dec | 9 +++++++++
>  MdeModulePkg/MdeModulePkg.uni | 6 ++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
> index 843e963ad34b..45874e9c8236 100644
> --- a/MdeModulePkg/MdeModulePkg.dec
> +++ b/MdeModulePkg/MdeModulePkg.dec
> @@ -1220,6 +1220,15 @@ [PcdsFixedAtBuild, PcdsPatchableInModule]
>    # @Prompt Shadow Peim and PeiCore on boot
>    gEfiMdeModulePkgTokenSpaceGuid.PcdShadowPeimOnBoot|TRUE|BOOLEAN|0x30001029
>  
> +  ## Enable the feature that evacuate temporary memory to permanent memory or not<BR><BR>
> +  #  Set FALSE as default, if the developer need this feature to avoid this vulnerability, please
> +  #  enable it to shadow all PEIMs no matter the behavior controled by PcdShadowPeimOnBoot or
> +  #  PcdShadowPeimOnS3Boot<BR>
> +  #  TRUE - Evacuate temporary memory, the actions include copy memory, convert PPI pointers and so on.<BR>
> +  #  FALSE - Do nothing, for example, no copy memory, no convert PPI pointers and so on.<BR>
> +  # @Prompt Evacuate temporary memory to permanent memory
> +  gEfiMdeModulePkgTokenSpaceGuid.PcdMigrateTemporaryRamFirmwareVolumes|FALSE|BOOLEAN|0x3000102A
> +
>    ## The mask is used to control memory profile behavior.<BR><BR>
>    #  BIT0 - Enable UEFI memory profile.<BR>
>    #  BIT1 - Enable SMRAM profile.<BR>
> diff --git a/MdeModulePkg/MdeModulePkg.uni b/MdeModulePkg/MdeModulePkg.uni
> index 2007e0596c4f..5235dee561ad 100644
> --- a/MdeModulePkg/MdeModulePkg.uni
> +++ b/MdeModulePkg/MdeModulePkg.uni
> @@ -214,6 +214,12 @@
>                                                                                         "TRUE  - Shadow PEIM on S3 boot path after memory is ready.<BR>\n"
>                                                                                         "FALSE - Not shadow PEIM on S3 boot path after memory is ready.<BR>"
>  
> +#string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdMigrateTemporaryRamFirmwareVolumes_HELP #language en-US "Enable the feature that evacuate temporary memory to permanent memory or not.<BR><BR>\n"
> +                                                                                                      "It will allocate page to save the temporary PEIMs resided in NEM(or CAR) to the permanent memory and change all pointers pointed to the NEM(or CAR) to permanent memory.<BR><BR>\n"
> +                                                                                                      "After then, there are no pointer pointed to NEM(or CAR) and TOCTOU volnerability can be avoid.<BR><BR>\n"
> +
> +#string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdMigrateTemporaryRamFirmwareVolumes_PROMPT #language en-US "Enable the feature that evacuate temporary memory to permanent memory or not"
> +
>  #string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultOemId_PROMPT  #language en-US "Default OEM ID for ACPI table creation"
>  
>  #string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultOemId_HELP  #language en-US "Default OEM ID for ACPI table creation, its length must be 0x6 bytes to follow ACPI specification."
> 

Acked-by: Laszlo Ersek <lersek@redhat.com>