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.
Cc: Jian J Wang <jian.j.w...@intel.com>
Cc: Hao A Wu <hao.a...@intel.com>
Signed-off-by: Guomin Jiang <guomin.ji...@intel.com>
---
MdeModulePkg/MdeModulePkg.dec | 7 +++++++
MdeModulePkg/MdeModulePkg.uni | 6 ++++++
2 files changed, 13 insertions(+)
diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 843e963ad34b..16db17d0a873 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -1220,6 +1220,13 @@ [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
+ # Set FALSE as default, if the developer need this feature to avoid this
vulnerability, please
+ # enable it in dsc file.
+ # TRUE - Evacuate temporary memory, the actions include copy memory, convert
PPI pointers and so on.
+ # FALSE - Do nothing, for example, no copy memory, no convert PPI pointers
and so on.
+
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."
--
2.25.1.windows.1
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