commit 19237091e3f57a9db0882bce942cb1ec56f9db2d
author nagendra modadugu <ngm@google.com> Fri May 12 02:11:33 2017 +0000
committer android-build-merger <android-build-merger@google.com> Fri May 12 02:11:33 2017 +0000
tree c0ffc44c5863a99b1c3324c0943b4d5526496031
parent 9695b44f9a6d08f31e48a90e23605dccd8187317
parent 07a9435803fa7709313a94419a0b94d2fe8ae27a

Rewrite MemoryEqual() to be constant-time. am: e760ff57b9 am: a71795a2cd
am: 07a9435803

Change-Id: I7c9ac4a9973aa33890034a544a5aec0cf3f5c8a2

MemoryLib.c

diff --git a/MemoryLib.c b/MemoryLib.c
index 7beac63..178848e 100644
--- a/MemoryLib.c
+++ b/MemoryLib.c
@@ -75,15 +75,15 @@
       UINT32            size                 // IN: size of bytes being compared
       )
 {
-      BOOL          equal = TRUE;
+      BOOL          diff = FALSE;
       const BYTE   *b1, *b2;
       b1 = (BYTE *)buffer1;
       b2 = (BYTE *)buffer2;
       // Compare all bytes so that there is no leakage of information
       // due to timing differences.
       for(; size > 0; size--)
-          equal = (*b1++ == *b2++) && equal;
-      return equal;
+          diff |= *b1++ ^ *b2++;
+      return !diff;
 }
 //
 //