src: no abort from getter if object isn't wrapped

v8::Object::GetAlignedPointerFromInternalField() returns a random value
if Wrap() hasn't been run on the object handle. Causing v8 to abort if
certain getters are accessed. It's possible to access these getters and
functions during class construction through the AsyncWrap init()
callback, and also possible in a subset of those scenarios while running
the persistent handle visitor.

Mitigate this issue by manually setting the internal aligned pointer
field to nullptr in the BaseObject constructor and add necessary logic
to return appropriate values when nullptr is encountered.

PR-URL: https://github.com/nodejs/node/pull/6184
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 10 insertions, 5 deletions

diff --git a/src/node_zlib.cc b/src/node_zlib.cc
index aee1cbae95..4de9d7cdc2 100644
--- a/src/node_zlib.cc
+++ b/src/node_zlib.cc
@@ -109,7 +109,8 @@ class ZCtx : public AsyncWrap {
 
 
   static void Close(const FunctionCallbackInfo<Value>& args) {
-    ZCtx* ctx = Unwrap<ZCtx>(args.Holder());
+    ZCtx* ctx;
+    ASSIGN_OR_RETURN_UNWRAP(&ctx, args.Holder());
     ctx->Close();
   }
 
@@ -119,7 +120,8 @@ class ZCtx : public AsyncWrap {
   static void Write(const FunctionCallbackInfo<Value>& args) {
     CHECK_EQ(args.Length(), 7);
 
-    ZCtx* ctx = Unwrap<ZCtx>(args.Holder());
+    ZCtx* ctx;
+    ASSIGN_OR_RETURN_UNWRAP(&ctx, args.Holder());
     CHECK(ctx->init_done_ && "write before init");
     CHECK(ctx->mode_ != NONE && "already finalized");
 
@@ -431,7 +433,8 @@ class ZCtx : public AsyncWrap {
     CHECK((args.Length() == 4 || args.Length() == 5) &&
            "init(windowBits, level, memLevel, strategy, [dictionary])");
 
-    ZCtx* ctx = Unwrap<ZCtx>(args.Holder());
+    ZCtx* ctx;
+    ASSIGN_OR_RETURN_UNWRAP(&ctx, args.Holder());
 
     int windowBits = args[0]->Uint32Value();
     CHECK((windowBits >= 8 && windowBits <= 15) && "invalid windowBits");
@@ -467,12 +470,14 @@ class ZCtx : public AsyncWrap {
 
   static void Params(const FunctionCallbackInfo<Value>& args) {
     CHECK(args.Length() == 2 && "params(level, strategy)");
-    ZCtx* ctx = Unwrap<ZCtx>(args.Holder());
+    ZCtx* ctx;
+    ASSIGN_OR_RETURN_UNWRAP(&ctx, args.Holder());
     Params(ctx, args[0]->Int32Value(), args[1]->Int32Value());
   }
 
   static void Reset(const FunctionCallbackInfo<Value> &args) {
-    ZCtx* ctx = Unwrap<ZCtx>(args.Holder());
+    ZCtx* ctx;
+    ASSIGN_OR_RETURN_UNWRAP(&ctx, args.Holder());
     Reset(ctx);
     SetDictionary(ctx);
   }