[PATCH] D51788: [winasan] Reduce hotpatch prefix check to 8 bytes

[David Major via Phabricator via llvm-commits]

dmajor created this revision.
dmajor added a reviewer: rnk.
Herald added subscribers: Sanitizers, llvm-commits.

Same idea as r310419: The 8 byte nop is a suffix of the 9 byte nop, and we need at most 6 bytes.


Repository:
  rCRT Compiler Runtime

https://reviews.llvm.org/D51788

Files:
  lib/interception/interception_win.cc


Index: lib/interception/interception_win.cc
===================================================================
--- lib/interception/interception_win.cc
+++ lib/interception/interception_win.cc
@@ -223,8 +223,8 @@
   return true;
 }
 
-static const u8 kHintNop9Bytes[] = {
-  0x66, 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00
+static const u8 kHintNop8Bytes[] = {
+  0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00
 };
 
 template<class T>
@@ -239,8 +239,8 @@
 static bool FunctionHasPadding(uptr address, uptr size) {
   if (IsMemoryPadding(address - size, size))
     return true;
-  if (size <= sizeof(kHintNop9Bytes) &&
-      FunctionHasPrefix(address, kHintNop9Bytes))
+  if (size <= sizeof(kHintNop8Bytes) &&
+      FunctionHasPrefix(address, kHintNop8Bytes))
     return true;
   return false;
 }


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