typed arrays: fix 32 bit size/index overflow

Fix an out-of-bound read/write bug due to integer wrapping. Reported by
Dean McNamee.

src/v8_typed_array.cc

@@ -21,6 +21,7 @@
 
 #include <stdlib.h>  // calloc, etc
 #include <string.h>  // memmove
+#include <stdint.h>
 
 #include "v8_typed_array.h"
 #include "node_buffer.h"
@@ -722,11 +723,14 @@ class DataView {
     // TODO(deanm): All of these things should be cacheable.
     int element_size = SizeOfArrayElementForType(
         args.This()->GetIndexedPropertiesExternalArrayDataType());
-    int size = args.This()->GetIndexedPropertiesExternalArrayDataLength() *
+    assert(element_size > 0);
-               element_size;
+    int size = args.This()->GetIndexedPropertiesExternalArrayDataLength();
+    assert(size >= 0);
 
-    if (index + sizeof(T) > (unsigned)size)  // TODO(deanm): integer overflow.
+    if (static_cast<uint64_t>(index) + sizeof(T) >
+        static_cast<uint64_t>(size) * element_size) {
       return ThrowError("Index out of range.");
+    }
 
     void* ptr = args.This()->GetIndexedPropertiesExternalArrayData();
     return cTypeToValue<T>(getValue<T>(ptr, index, !little_endian));
@@ -742,11 +746,14 @@ class DataView {
     // TODO(deanm): All of these things should be cacheable.
     int element_size = SizeOfArrayElementForType(
         args.This()->GetIndexedPropertiesExternalArrayDataType());
-    int size = args.This()->GetIndexedPropertiesExternalArrayDataLength() *
+    assert(element_size > 0);
-               element_size;
+    int size = args.This()->GetIndexedPropertiesExternalArrayDataLength();
+    assert(size >= 0);
 
-    if (index + sizeof(T) > (unsigned)size)  // TODO(deanm): integer overflow.
+    if (static_cast<uint64_t>(index) + sizeof(T) >
+        static_cast<uint64_t>(size) * element_size) {
       return ThrowError("Index out of range.");
+    }
 
     void* ptr = args.This()->GetIndexedPropertiesExternalArrayData();
     setValue<T>(ptr, index, valueToCType<T>(args[1]), !little_endian);

test/simple/test-typed-arrays.js

@@ -182,3 +182,13 @@ assert.equal(uint8c[1], 255);
   var view = new DataView(array.buffer);
   for (var i = 128; i <= 255; ++i) assert.equal(view.getInt8(i - 128), i - 256);
 })();
+
+assert.throws(function() {
+  var buf = new DataView(new ArrayBuffer(8));
+  buf.getFloat64(0xffffffff, true);
+}, /Index out of range/);
+
+assert.throws(function() {
+  var buf = new DataView(new ArrayBuffer(8));
+  buf.setFloat64(0xffffffff, 0.0, true);
+}, /Index out of range/);