Fix unsafe unaligned accesses in the serializer/deserializer.

src/serialize.h

 // 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.
 
 #ifndef V8_SERIALIZE_H_
 #define V8_SERIALIZE_H_
 
 #include "src/compiler.h"
 #include "src/hashmap.h"
 #include "src/heap-profiler.h"
@@ skipping 464 matching lines @@
 
   ~SerializedData() {
     if (owns_data_) DeleteArray<byte>(data_);
   }
 
   class ChunkSizeBits : public BitField<uint32_t, 0, 31> {};
   class IsLastChunkBits : public BitField<bool, 31, 1> {};
 
  protected:
   void SetHeaderValue(int offset, int value) {
-    reinterpret_cast<int*>(data_)[offset] = value;
+    memcpy(reinterpret_cast<int*>(data_) + offset, &value, sizeof(value));
   }
 
   int GetHeaderValue(int offset) const {
-    return reinterpret_cast<const int*>(data_)[offset];
+    int value;
+    memcpy(&value, reinterpret_cast<int*>(data_) + offset, sizeof(value));
+    return value;
   }
 
   void AllocateData(int size);
 
   byte* data_;
   int size_;
   bool owns_data_;
 };
 
 
@@ skipping 37 matching lines @@
   virtual void VisitPointers(Object** start, Object** end);
 
   virtual void VisitRuntimeEntry(RelocInfo* rinfo) {
     UNREACHABLE();
   }
 
   void DecodeReservation(Vector<const SerializedData::Reservation> res);
 
   bool ReserveSpace();
 
+  void UnalignedCopy(Object** dest, Object** src) {
+    memcpy(dest, src, sizeof(*src));
+  }
+
   // Allocation sites are present in the snapshot, and must be linked into
   // a list at deserialization time.
   void RelinkAllocationSite(AllocationSite* site);
 
   // Fills in some heap data in an area from start to end (non-inclusive).  The
   // space id is used for the write barrier.  The object_address is the address
   // of the object we are writing into, or NULL if we are not writing into an
   // object, i.e. if we are writing a series of tagged values that are not on
   // the heap.
   void ReadData(Object** start, Object** end, int space,
@@ skipping 376 matching lines @@
   static const int kCheckSumOffset = 0;
   static const int kNumInternalizedStringsOffset = 1;
   static const int kReservationsOffset = 2;
   static const int kNumCodeStubKeysOffset = 3;
   static const int kPayloadLengthOffset = 4;
   static const int kHeaderSize = (kPayloadLengthOffset + 1) * kIntSize;
 };
 } }  // namespace v8::internal
 
 #endif  // V8_SERIALIZE_H_