[edk2-devel] [PATCH v2] OvmfPkg/MemEncryptSevLib: Fix address overflow during PVALIDATE

["Roth, Michael via groups.io" <Michael.Roth=amd.com@groups.io>]

The struct used for GHCB-based page-state change requests uses a 40-bit
bit-field for the GFN, which is shifted by PAGE_SHIFT to generate a
64-bit address. However, anything beyond 40-bits simply gets shifted off
when doing this, which will cause issues when dealing with 1TB+
addresses. Fix this by casting the 40-bit GFN values to 64-bit ones
prior to shifting it by PAGE_SHIFT.

Fixes: ade62c18f474 ("OvmfPkg/MemEncryptSevLib: add support to validate system RAM")
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
v2:
  - use EFI_PHYSICAL_ADDRESS instead of UINT64 (Gerd)

 .../BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c    | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
index 85eb41585b..46c6682760 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
@@ -78,13 +78,14 @@ PvalidateRange (
   IN  BOOLEAN                     Validate

   )

 {

-  UINTN  Address, RmpPageSize, Ret, i;

+  UINTN                 RmpPageSize, Ret, i;

+  EFI_PHYSICAL_ADDRESS  Address;

 

   for ( ; StartIndex <= EndIndex; StartIndex++) {

     //

     // Get the address and the page size from the Info.

     //

-    Address     = Info->Entry[StartIndex].GuestFrameNumber << EFI_PAGE_SHIFT;

+    Address     = ((EFI_PHYSICAL_ADDRESS)Info->Entry[StartIndex].GuestFrameNumber) << EFI_PAGE_SHIFT;

     RmpPageSize = Info->Entry[StartIndex].PageSize;

 

     Ret = AsmPvalidate (RmpPageSize, Validate, Address);

-- 
2.25.1



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