MmCoreFfsFindMmDriver() is called recursively for encapsulation sections.
Currently this recursion is not limited. Introduce a new PCD
(fixed-at-build, or patchable-in-module), and make MmCoreFfsFindMmDriver()
track the section nesting depth against that PCD.
Cc: Laszlo Ersek <ler...@redhat.com>
Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org>
Cc: Sami Mujawar <sami.muja...@arm.com>
Cc: Ray Ni <ray...@intel.com>
Signed-off-by: Wei6 Xu <wei6...@intel.com>
---
StandaloneMmPkg/Core/FwVol.c | 16 ++++++++++++++--
StandaloneMmPkg/Core/StandaloneMmCore.c | 5 +++--
StandaloneMmPkg/Core/StandaloneMmCore.inf | 3 +++
StandaloneMmPkg/StandaloneMmPkg.dec | 5 +++++
4 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/StandaloneMmPkg/Core/FwVol.c b/StandaloneMmPkg/Core/FwVol.c
index 1f6d7714ba97..e1e20ffd14ac 100644
--- a/StandaloneMmPkg/Core/FwVol.c
+++ b/StandaloneMmPkg/Core/FwVol.c
@@ -48,6 +48,9 @@ FvIsBeingProcessed (
MM driver and return its PE32 image.
@param [in] FwVolHeader Pointer to memory mapped FV
+ @param [in] Depth Nesting depth of encapsulation sections. Callers
+ different from MmCoreFfsFindMmDriver() are
+ responsible for passing in a zero Depth.
@retval EFI_SUCCESS Success.
@retval EFI_INVALID_PARAMETER Invalid parameter.
@@ -55,11 +58,15 @@ FvIsBeingProcessed (
@retval EFI_OUT_OF_RESOURCES Out of resources.
@retval EFI_VOLUME_CORRUPTED Firmware volume is corrupted.
@retval EFI_UNSUPPORTED Operation not supported.
+ @retval EFI_ABORTED Recursion aborted because Depth has been
+ greater than or equal to
+ PcdFwVolMmMaxEncapsulationDepth.
**/
EFI_STATUS
MmCoreFfsFindMmDriver (
- IN EFI_FIRMWARE_VOLUME_HEADER *FwVolHeader
+ IN EFI_FIRMWARE_VOLUME_HEADER *FwVolHeader,
+ IN UINT32 Depth
)
{
EFI_STATUS Status;
@@ -84,6 +91,11 @@ MmCoreFfsFindMmDriver (
DEBUG ((DEBUG_INFO, "MmCoreFfsFindMmDriver - 0x%x\n", FwVolHeader));
+ if (Depth >= PcdGet32 (PcdFwVolMmMaxEncapsulationDepth)) {
+ DEBUG ((DEBUG_ERROR, "%a: recursion aborted due to nesting depth\n",
__func__));
+ return EFI_ABORTED;
+ }
+
if (FvHasBeenProcessed (FwVolHeader)) {
return EFI_SUCCESS;
}
@@ -172,7 +184,7 @@ MmCoreFfsFindMmDriver (
}
InnerFvHeader = (VOID *)(Section + 1);
- Status = MmCoreFfsFindMmDriver (InnerFvHeader);
+ Status = MmCoreFfsFindMmDriver (InnerFvHeader, Depth + 1);
if (EFI_ERROR (Status)) {
goto FreeDstBuffer;
}
diff --git a/StandaloneMmPkg/Core/StandaloneMmCore.c
b/StandaloneMmPkg/Core/StandaloneMmCore.c
index d221f1d1115d..523ea0a632a1 100644
--- a/StandaloneMmPkg/Core/StandaloneMmCore.c
+++ b/StandaloneMmPkg/Core/StandaloneMmCore.c
@@ -11,7 +11,8 @@
EFI_STATUS
MmCoreFfsFindMmDriver (
- IN EFI_FIRMWARE_VOLUME_HEADER *FwVolHeader
+ IN EFI_FIRMWARE_VOLUME_HEADER *FwVolHeader,
+ IN UINT32 Depth
);
EFI_STATUS
@@ -643,7 +644,7 @@ StandaloneMmMain (
//
DEBUG ((DEBUG_INFO, "Mm Dispatch StandaloneBfvAddress - 0x%08x\n",
gMmCorePrivate->StandaloneBfvAddress));
if (gMmCorePrivate->StandaloneBfvAddress != 0) {
- MmCoreFfsFindMmDriver ((EFI_FIRMWARE_VOLUME_HEADER
*)(UINTN)gMmCorePrivate->StandaloneBfvAddress);
+ MmCoreFfsFindMmDriver ((EFI_FIRMWARE_VOLUME_HEADER
*)(UINTN)gMmCorePrivate->StandaloneBfvAddress, 0);
MmDispatcher ();
}
diff --git a/StandaloneMmPkg/Core/StandaloneMmCore.inf
b/StandaloneMmPkg/Core/StandaloneMmCore.inf
index c44b9ff33303..02ecd68f37e2 100644
--- a/StandaloneMmPkg/Core/StandaloneMmCore.inf
+++ b/StandaloneMmPkg/Core/StandaloneMmCore.inf
@@ -76,6 +76,9 @@ [Guids]
gEfiEventExitBootServicesGuid
gEfiEventReadyToBootGuid
+[Pcd]
+ gStandaloneMmPkgTokenSpaceGuid.PcdFwVolMmMaxEncapsulationDepth ##CONSUMES
+
#
# This configuration fails for CLANGPDB, which does not support PIE in the GCC
# sense. Such however is required for ARM family StandaloneMmCore
diff --git a/StandaloneMmPkg/StandaloneMmPkg.dec
b/StandaloneMmPkg/StandaloneMmPkg.dec
index 46784d94e421..c43632d6d8ae 100644
--- a/StandaloneMmPkg/StandaloneMmPkg.dec
+++ b/StandaloneMmPkg/StandaloneMmPkg.dec
@@ -48,3 +48,8 @@ [Guids]
gEfiStandaloneMmNonSecureBufferGuid = { 0xf00497e3, 0xbfa2, 0x41a1, {
0x9d, 0x29, 0x54, 0xc2, 0xe9, 0x37, 0x21, 0xc5 }}
gEfiArmTfCpuDriverEpDescriptorGuid = { 0x6ecbd5a1, 0xc0f8, 0x4702, {
0x83, 0x01, 0x4f, 0xc2, 0xc5, 0x47, 0x0a, 0x51 }}
+[PcdsFixedAtBuild, PcdsPatchableInModule]
+ ## Maximum permitted encapsulation levels of sections in a firmware volume,
+ # in the MM phase. Minimum value is 1. Sections nested more deeply are
rejected.
+ # @Prompt Maximum permitted FwVol section nesting depth (exclusive) in MM.
+
gStandaloneMmPkgTokenSpaceGuid.PcdFwVolMmMaxEncapsulationDepth|0x10|UINT32|0x00000001
--
2.29.2.windows.2
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