[Backport] CVE-2020-6426: Inappropriate implementation in V8.

Manual backport of patch originally reviewed on:
https://chromium-review.googlesource.com/c/v8/v8/+/2104887

Merged: [intl] Fix Intl.NumberFormat constructor

Revision: 09d14728ca251c955f4634036f8d72a4665e96c6

BUG=chromium:1052647
NOTRY=true
NOPRESUBMIT=true
NOTREECHECKS=true

Change-Id: Iff7dbf9e6e3b071d5a98e61120f5c2aa69affe7f
Reviewed-by: Michal Klocek <michal.klocek@qt.io>

1 files changed, 36 insertions, 41 deletions

diff --git a/chromium/v8/src/builtins/builtins-intl.cc b/chromium/v8/src/builtins/builtins-intl.cc
index ff8e96f4f51..d75049fdb29 100644
--- a/chromium/v8/src/builtins/builtins-intl.cc
+++ b/chromium/v8/src/builtins/builtins-intl.cc
@@ -269,10 +269,8 @@ Object LegacyFormatConstructor(BuiltinArguments args, Isolate* isolate,
 
   // [[Construct]]
   Handle<JSFunction> target = args.target();
-
   Handle<Object> locales = args.atOrUndefined(isolate, 1);
   Handle<Object> options = args.atOrUndefined(isolate, 2);
-
   // 2. Let format be ? OrdinaryCreateFromConstructor(newTarget,
   // "%<T>Prototype%", ...).
 
@@ -285,45 +283,42 @@ Object LegacyFormatConstructor(BuiltinArguments args, Isolate* isolate,
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, format,
                                      T::New(isolate, map, locales, options));
   // 4. Let this be the this value.
-  Handle<Object> receiver = args.receiver();
-
-  // 5. If NewTarget is undefined and ? InstanceofOperator(this, %<T>%)
-  // is true, then
-  //
-  // Look up the intrinsic value that has been stored on the context.
-  // Call the instanceof function
-  Handle<Object> is_instance_of_obj;
-  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-      isolate, is_instance_of_obj,
-      Object::InstanceOf(isolate, receiver, constructor));
-
-  // Get the boolean value of the result
-  bool is_instance_of = is_instance_of_obj->BooleanValue(isolate);
-
-  if (args.new_target()->IsUndefined(isolate) && is_instance_of) {
-    if (!receiver->IsJSReceiver()) {
-      THROW_NEW_ERROR_RETURN_FAILURE(
-          isolate,
-          NewTypeError(MessageTemplate::kIncompatibleMethodReceiver,
-                       isolate->factory()->NewStringFromAsciiChecked(method),
-                       receiver));
-    }
-    Handle<JSReceiver> rec = Handle<JSReceiver>::cast(receiver);
-    // a. Perform ? DefinePropertyOrThrow(this,
-    // %Intl%.[[FallbackSymbol]], PropertyDescriptor{ [[Value]]: format,
-    // [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }).
-    PropertyDescriptor desc;
-    desc.set_value(format);
-    desc.set_writable(false);
-    desc.set_enumerable(false);
-    desc.set_configurable(false);
-    Maybe<bool> success = JSReceiver::DefineOwnProperty(
-        isolate, rec, isolate->factory()->intl_fallback_symbol(), &desc,
-        Just(kThrowOnError));
-    MAYBE_RETURN(success, ReadOnlyRoots(isolate).exception());
-    CHECK(success.FromJust());
-    // b. b. Return this.
-    return *receiver;
+  if (args.new_target()->IsUndefined(isolate)) {
+    Handle<Object> receiver = args.receiver();
+
+    // 5. If NewTarget is undefined and ? InstanceofOperator(this, %<T>%)
+    // is true, then Look up the intrinsic value that has been stored on
+    // the context.
+    Handle<Object> is_instance_of_obj;
+    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+        isolate, is_instance_of_obj,
+        Object::InstanceOf(isolate, receiver, constructor));
+
+    if (is_instance_of_obj->BooleanValue(isolate)) {
+      if (!receiver->IsJSReceiver()) {
+        THROW_NEW_ERROR_RETURN_FAILURE(
+            isolate,
+            NewTypeError(MessageTemplate::kIncompatibleMethodReceiver,
+                         isolate->factory()->NewStringFromAsciiChecked(method),
+                         receiver));
+      }
+      Handle<JSReceiver> rec = Handle<JSReceiver>::cast(receiver);
+      // a. Perform ? DefinePropertyOrThrow(this,
+      // %Intl%.[[FallbackSymbol]], PropertyDescriptor{ [[Value]]: format,
+      // [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }).
+      PropertyDescriptor desc;
+      desc.set_value(format);
+      desc.set_writable(false);
+      desc.set_enumerable(false);
+      desc.set_configurable(false);
+      Maybe<bool> success = JSReceiver::DefineOwnProperty(
+         isolate, rec, isolate->factory()->intl_fallback_symbol(), &desc,
+          Just(kThrowOnError));
+      MAYBE_RETURN(success, ReadOnlyRoots(isolate).exception());
+      CHECK(success.FromJust());
+      // b. b. Return this.
+      return *receiver;
+     }
   }
   // 6. Return format.
   return *format;