https://bugzilla.tianocore.org/show_bug.cgi?id=2525
SafeUint64Mult() looks for 64-bit overflows and performs
several 32-bit multiples with 64-bit results to check for
all possible overflow conditions. IA32 builds using VS20xx
with optimizations enabled are producing a reference to
the _allmull intrinsic.
The fix is to use MultU64x64() instead of '*' for
these operations. These are safe because the inputs
are guaranteed to have the upper 32-bits clear, which
means MultU64x64() can never overflow with those inputs.
Cc: Liming Gao <liming....@intel.com>
Cc: Sean Brogan <sean.bro...@microsoft.com>
Cc: Bret Barkelew <bret.barke...@microsoft.com>
Signed-off-by: Michael D Kinney <michael.d.kin...@intel.com>
---
MdePkg/Library/BaseSafeIntLib/SafeIntLib.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
b/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
index 0f6be6e064..eec8ac1ffd 100644
--- a/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
+++ b/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
@@ -3380,14 +3380,14 @@ SafeUint64Mult (
//
// a * d must be less than 2^32 or there would be bits set in the high
64-bits
//
- ProductAD = (((UINT64)DwordA) *(UINT64)DwordD);
+ ProductAD = MultU64x64 ((UINT64)DwordA, (UINT64)DwordD);
if ((ProductAD & 0xffffffff00000000) == 0) {
DwordB = (UINT32)Multiplicand;
//
// b * c must be less than 2^32 or there would be bits set in the high
64-bits
//
- ProductBC = (((UINT64)DwordB) *(UINT64)DwordC);
+ ProductBC = MultU64x64 ((UINT64)DwordB, (UINT64)DwordC);
if ((ProductBC & 0xffffffff00000000) == 0) {
//
// now sum them all up checking for overflow.
@@ -3397,7 +3397,7 @@ SafeUint64Mult (
//
// b * d
//
- ProductBD = (((UINT64)DwordB) *(UINT64)DwordD);
+ ProductBD = MultU64x64 ((UINT64)DwordB, (UINT64)DwordD);
if (!RETURN_ERROR (SafeUint64Add (UnsignedResult, ProductBD,
&UnsignedResult))) {
*Result = UnsignedResult;
--
2.21.0.windows.1
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