Ensure that executable pages are properly guarded.

src/platform-cygwin.cc

Index: src/platform-cygwin.cc
diff --git a/src/platform-cygwin.cc b/src/platform-cygwin.cc
index 79134da35255b529e95920fc6542116fe9402dba..2dc1ed89db087cc1db5f4eb2f3421fe3d1dc9831 100644
--- a/src/platform-cygwin.cc
+++ b/src/platform-cygwin.cc
@@ -355,6 +355,17 @@ bool VirtualMemory::Uncommit(void* address, size_t size) {
 }
 
 
+bool VirtualMemory::Guard(void* address) {
+  if (NULL == VirtualAlloc(address,
+                           OS::CommitPageSize(),
+                           MEM_COMMIT,
+                           PAGE_READONLY | PAGE_GUARD)) {

[Erik Corry, 2012/02/23 12:00:40]

Can we not map it with no permissions at all, instead of read only?

+    return false;
+  }
+  return true;
+}
+
+
 class Thread::PlatformData : public Malloced {
  public:
   PlatformData() : thread_(kNoThread) {}