Add RuntimeConfig option to disable ArrayBuffer et al.

Summary: Add a RuntimeConfig option to disable ArrayBuffer, DataView and all typed arrays. When disabled, the constructors are absent from the global object, and none of their methods are even defined. As a last line of defense, the process will terminate if an ArrayBuffer is somehow still accessed. Reviewed By: neildhar Differential Revision: D37470100 fbshipit-source-id: 289b3eee3afd9f24bcddc46c9bc381c410cf20e1
ayroblu · Jun 28, 2022 · 4779dd1 · 4779dd1
1 parent b823515
commit 4779dd1
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Showing 5 changed files with 26 additions and 7 deletions.
diff --git a/include/hermes/VM/JSArrayBuffer.h b/include/hermes/VM/JSArrayBuffer.h
@@ -68,6 +68,10 @@ class JSArrayBuffer final : public JSObject {
   ///   if the ArrayBuffer is empty.
   /// \pre attached() must be true
   uint8_t *getDataBlock(Runtime &runtime) {
+    // This check should never fail, because all ways to illegally access
+    // ArrayBuffer should raise exceptions. It's here as a last line of defense.
+    if (!runtime.hasArrayBuffer())
+      hermes_fatal("Illegal access to ArrayBuffer");
     assert(attached() && "Cannot get a data block from a detached ArrayBuffer");
     return data_.get(runtime);
   }

diff --git a/include/hermes/VM/Runtime.h b/include/hermes/VM/Runtime.h
@@ -852,6 +852,10 @@ class Runtime : public PointerBase,
     return hasIntl_;
   }
 
+  bool hasArrayBuffer() const {
+    return hasArrayBuffer_;
+  }
+
   bool useJobQueue() const {
     return getVMExperimentFlags() & experiments::JobQueue;
   }
@@ -1117,6 +1121,9 @@ class Runtime : public PointerBase,
   /// Set to true if we should enable ECMA-402 Intl APIs.
   const bool hasIntl_;
 
+  /// Set to true if we should enable ArrayBuffer, DataView and typed arrays.
+  const bool hasArrayBuffer_;
+
   /// Set to true if we should randomize stack placement etc.
   const bool shouldRandomizeMemoryLayout_;
 

diff --git a/lib/VM/JSLib/GlobalObject.cpp b/lib/VM/JSLib/GlobalObject.cpp
@@ -587,21 +587,25 @@ void initGlobalObject(Runtime &runtime, const JSLibFlags &jsLibFlags) {
   // Array constructor.
   createArrayConstructor(runtime);
 
-  // ArrayBuffer constructor.
-  createArrayBufferConstructor(runtime);
+  if (runtime.hasArrayBuffer()) {
+    // ArrayBuffer constructor.
+    createArrayBufferConstructor(runtime);
 
-  // DataView constructor.
-  createDataViewConstructor(runtime);
+    // DataView constructor.
+    createDataViewConstructor(runtime);
 
-  // TypedArrayBase constructor.
-  runtime.typedArrayBaseConstructor =
-      createTypedArrayBaseConstructor(runtime).getHermesValue();
+    // TypedArrayBase constructor.
+    runtime.typedArrayBaseConstructor =
+        createTypedArrayBaseConstructor(runtime).getHermesValue();
 
 #define TYPED_ARRAY(name, type)                                 \
   runtime.name##ArrayConstructor =                              \
       create##name##ArrayConstructor(runtime).getHermesValue(); \
   gcScope.clearAllHandles();
 #include "hermes/VM/TypedArrays.def"
+  } else {
+    gcScope.clearAllHandles();
+  } // hasArrayBuffer
 
   // Set constructor.
   createSetConstructor(runtime);

diff --git a/lib/VM/Runtime.cpp b/lib/VM/Runtime.cpp
@@ -224,6 +224,7 @@ Runtime::Runtime(
       hasES6Promise_(runtimeConfig.getES6Promise()),
       hasES6Proxy_(runtimeConfig.getES6Proxy()),
       hasIntl_(runtimeConfig.getIntl()),
+      hasArrayBuffer_(runtimeConfig.getArrayBuffer()),
       shouldRandomizeMemoryLayout_(runtimeConfig.getRandomizeMemoryLayout()),
       bytecodeWarmupPercent_(runtimeConfig.getBytecodeWarmupPercent()),
       trackIO_(runtimeConfig.getTrackIO()),

diff --git a/public/hermes/Public/RuntimeConfig.h b/public/hermes/Public/RuntimeConfig.h
@@ -61,6 +61,9 @@ class PinnedHermesValue;
   /* Support for ECMA-402 Intl APIs. */                                \
   F(constexpr, bool, Intl, true)                                       \
                                                                        \
+  /* Support for ArrayBuffer, DataView and typed arrays. */            \
+  F(constexpr, bool, ArrayBuffer, true)                                \
+                                                                       \
   /* Enable synth trace. */                                            \
   F(constexpr, bool, TraceEnabled, false)                              \
                                                                        \