Disable VirtualAlloc randomization on 32-bit Windows hosts

src/base/platform/platform-win32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Platform-specific code for Win32.
 
 // Secure API functions are not available using MinGW with msvcrt.dll
 // on Windows XP. Make sure MINGW_HAS_SECURE_API is not defined to
 // disable definition of secure API functions in standard headers that
 // would conflict with our own implementation.
@@ skipping 733 matching lines @@
                                                         sizeof(address));
   address <<= kPageSizeBits;
   address += kAllocationRandomAddressMin;
   address &= kAllocationRandomAddressMax;
   return reinterpret_cast<void *>(address);
 }
 
 
 static void* RandomizedVirtualAlloc(size_t size, int action, int protection) {
   LPVOID base = NULL;
+  static BOOL use_aslr = -1;
+#ifdef V8_HOST_ARCH_32_BIT
+  // Don't bother randomizing on 32-bit hosts, because they lack the room and
+  // don't have viable ASLR anyway.
+  if (use_aslr == -1 && !IsWow64Process(GetCurrentProcess(), &use_aslr))
+    use_aslr = FALSE;
+#else
+  use_aslr = TRUE;
+#endif
 
-  if (protection == PAGE_EXECUTE_READWRITE || protection == PAGE_NOACCESS) {
-    // For exectutable pages try and randomize the allocation address
+  if (use_aslr &&
+      (protection == PAGE_EXECUTE_READWRITE || protection == PAGE_NOACCESS)) {
+    // For executable pages try and randomize the allocation address
     for (size_t attempts = 0; base == NULL && attempts < 3; ++attempts) {
       base = VirtualAlloc(OS::GetRandomMmapAddr(), size, action, protection);
     }
   }
 
   // After three attempts give up and let the OS find an address to use.
   if (base == NULL) base = VirtualAlloc(NULL, size, action, protection);
 
   return base;
 }
@@ skipping 612 matching lines @@
 
 
 void Thread::SetThreadLocal(LocalStorageKey key, void* value) {
   BOOL result = TlsSetValue(static_cast<DWORD>(key), value);
   USE(result);
   DCHECK(result);
 }
 
 }  // namespace base
 }  // namespace v8