Relocations of types EFI_IMAGE_REL_BASED_HIGH and EFI_IMAGE_REL_BASED_LOW
occur in pairs, where each of the pair relocates a 16-bit word half of a
32-bit dword.
Since the target of the relocation arithmetic is a 32-bit quantity,
we should handle a carry that may occur in the low word relocation,
by taking the carry into account when relocating the high word.
Since we know the relocation pair refers to a single value, we can
simply perform the addition for the entire value when handling the high
relocation, and truncate the result to 16-bits.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
---
MdePkg/Library/BasePeCoffLib/BasePeCoff.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/MdePkg/Library/BasePeCoffLib/BasePeCoff.c
b/MdePkg/Library/BasePeCoffLib/BasePeCoff.c
index 33cad23a014e..28c84062d125 100644
--- a/MdePkg/Library/BasePeCoffLib/BasePeCoff.c
+++ b/MdePkg/Library/BasePeCoffLib/BasePeCoff.c
@@ -1103,7 +1103,8 @@ PeCoffLoaderRelocateImage (
case EFI_IMAGE_REL_BASED_HIGH:
Fixup16 = (UINT16 *) Fixup;
- *Fixup16 = (UINT16) (*Fixup16 + ((UINT16) ((UINT32) Adjust >> 16)));
+ Fixup32 = (UINT32 *) (Fixup16 - 1);
+ *Fixup16 = (UINT16) ((*Fixup32 + (UINT32) Adjust) >> 16);
if (FixupData != NULL) {
*(UINT16 *) FixupData = *Fixup16;
FixupData = FixupData + sizeof (UINT16);
@@ -1828,8 +1829,9 @@ PeCoffLoaderRelocateImageForRuntime (
case EFI_IMAGE_REL_BASED_HIGH:
Fixup16 = (UINT16 *) Fixup;
+ Fixup32 = (UINT32 *) (Fixup16 - 1);
if (*(UINT16 *) FixupData == *Fixup16) {
- *Fixup16 = (UINT16) (*Fixup16 + ((UINT16) ((UINT32) Adjust >> 16)));
+ *Fixup16 = (UINT16) ((*Fixup32 + (UINT32) Adjust) >> 16);
}
FixupData = FixupData + sizeof (UINT16);
--
1.9.1
------------------------------------------------------------------------------
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