Address Sanitizer tests failing with ES6 Classes

[Beanyy]

Bug Description

I'm running address sanitization tests on our code base with Hermes and I'm encountering a consistent stack-use-after-scope errors with ES6 classes. I've narrowed down the issue to the code here:

hermes/lib/AST/ES6Class.cpp

Lines 58 to 65 in 7991309

 ESTree::NodeList toNodeList() const { 
   ESTree::NodeList nodeList; 
   for (auto &node : _storage) { 
     nodeList.push_back(*node); 
   } 
  
   return nodeList; 
 } 

One of the calling functions makeHermesES6InternalCall calls toNodeList which returned an ESTree::NodeList that was allocated on the stack. Changing the code such that the ESTree::NodeList is created on the stack of makeHermesES6InternalCall instead fixes the ASAN error. I'm not 100% sure why this is happening and it may be due to some compiler specific optimizations.

hermes/lib/AST/ES6Class.cpp

Lines 400 to 412 in 7991309

 ESTree::Node *makeHermesES6InternalCall( 
     ESTree::Node *srcNode, 
     llvh::StringRef methodName, 
     const NodeVector &parameters) { 
   auto hermesInternalIdentifier = 
       makeIdentifierNode(srcNode, "HermesES6Internal"); 
   auto methodIdentifier = makeIdentifierNode(srcNode, methodName); 
  
   auto *getPropertyNode = createTransformedNode<ESTree::MemberExpressionNode>( 
       srcNode, hermesInternalIdentifier, methodIdentifier, false); 
   return createTransformedNode<ESTree::CallExpressionNode>( 
       srcNode, getPropertyNode, nullptr, parameters.toNodeList()); 
 } 

It creates a little bit a repetitiveness but removing the toNodeList function (and replacing the calling sites with the appropriate fix) resolved the issue entirely for me.

Let me know what you think.

---

• I have run gradle clean and confirmed this bug does not occur with JSC
• The issue is reproducible with the latest version of React Native.

Hermes git revision (if applicable):
React Native version:
OS:
Platform (most likely one of arm64-v8a, armeabi-v7a, x86, x86_64):

Steps To Reproduce

code example:

The Expected Behavior

[Tzvetan Mikov]

Thank you for catching this!

This is a compiler bug in Apple CLang. It was worked around in Static Hermes in b6a791c, but we must have forgotten to backport it to Hermes.

We will backport the fix.

Please note that the ES6 classes AST transform is undocumented and unsupported. But it still shouldn't crash :-)

[Beanyy]

Thanks! That fixed the issue.