Fixed fuzzer app and ensured that React does not crash when fuzzed

Libraries/Utilities/MessageQueue.js

@@ -218,9 +218,10 @@ class MessageQueue {
       return null;
     }
 
+    let fn = null;
     let self = this;
     if (type === MethodTypes.remoteAsync) {
-      return function(...args) {
+      fn = function(...args) {
         return new Promise((resolve, reject) => {
           self.__nativeCall(module, method, args, resolve, (errorData) => {
             var error = createErrorFromErrorData(errorData);
@@ -229,7 +230,7 @@ class MessageQueue {
         });
       };
     } else {
-      return function(...args) {
+      fn = function(...args) {
         let lastArg = args.length > 0 ? args[args.length - 1] : null;
         let secondLastArg = args.length > 1 ? args[args.length - 2] : null;
         let hasSuccCB = typeof lastArg === 'function';
@@ -245,6 +246,8 @@ class MessageQueue {
         return self.__nativeCall(module, method, args, onFail, onSucc);
       };
     }
+    fn.type = type;
+    return fn;
   }
 
 }

React/Base/RCTModuleMethod.m

@@ -17,7 +17,7 @@
 #import "RCTLog.h"
 #import "RCTUtils.h"
 
-typedef void (^RCTArgumentBlock)(RCTBridge *, NSUInteger, id);
+typedef BOOL (^RCTArgumentBlock)(RCTBridge *, NSUInteger, id);
 
 @implementation RCTMethodArgument
 
@@ -166,6 +166,7 @@ void RCTParseObjCMethodName(NSString **objCMethodName, NSArray **arguments)
 [argumentBlocks addObject:^(__unused RCTBridge *bridge, NSUInteger index, id json) { \
   _logic \
   [invocation setArgument:&value atIndex:(index) + 2]; \
+  return YES; \
 }];
 
   __weak RCTModuleMethod *weakSelf = self;
@@ -174,7 +175,7 @@ void RCTParseObjCMethodName(NSString **objCMethodName, NSArray **arguments)
 
       if (RCT_DEBUG && json && ![json isKindOfClass:[NSNumber class]]) {
         RCTLogArgumentError(weakSelf, index, json, "should be a function");
-        return;
+        return NO;
       }
 
       // Marked as autoreleasing, because NSInvocation doesn't retain arguments
@@ -268,13 +269,13 @@ void RCTParseObjCMethodName(NSString **objCMethodName, NSArray **arguments)
 
         if (RCT_DEBUG && json && ![json isKindOfClass:[NSNumber class]]) {
           RCTLogArgumentError(weakSelf, index, json, "should be a function");
-          return;
+          return NO;
         }
 
         // Marked as autoreleasing, because NSInvocation doesn't retain arguments
         __autoreleasing id value = (json ? ^(NSError *error) {
           [bridge _invokeAndProcessModule:@"BatchedBridge"
-                                   method:@"invokeCallbackAndReturnFlushedQueue"
+                                     method:@"invokeCallbackAndReturnFlushedQueue"
                                 arguments:@[json, @[RCTJSErrorFromNSError(error)]]];
         } : ^(__unused NSError *error) {});
       )
@@ -285,7 +286,7 @@ void RCTParseObjCMethodName(NSString **objCMethodName, NSArray **arguments)
       RCT_ARG_BLOCK(
         if (RCT_DEBUG && ![json isKindOfClass:[NSNumber class]]) {
           RCTLogArgumentError(weakSelf, index, json, "should be a promise resolver function");
-          return;
+          return NO;
         }
 
         // Marked as autoreleasing, because NSInvocation doesn't retain arguments
@@ -302,7 +303,7 @@ void RCTParseObjCMethodName(NSString **objCMethodName, NSArray **arguments)
       RCT_ARG_BLOCK(
         if (RCT_DEBUG && ![json isKindOfClass:[NSNumber class]]) {
           RCTLogArgumentError(weakSelf, index, json, "should be a promise rejecter function");
-          return;
+          return NO;
         }
 
         // Marked as autoreleasing, because NSInvocation doesn't retain arguments
@@ -350,12 +351,11 @@ void RCTParseObjCMethodName(NSString **objCMethodName, NSArray **arguments)
       if (nullability == RCTNonnullable) {
         RCTArgumentBlock oldBlock = argumentBlocks[i - 2];
         argumentBlocks[i - 2] = ^(RCTBridge *bridge, NSUInteger index, id json) {
-          if (json == nil || json == (id)kCFNull) {
+          if (json == nil) {
             RCTLogArgumentError(weakSelf, index, typeName, "must not be null");
-            id null = nil;
-            [invocation setArgument:&null atIndex:index + 2];
+            return NO;
           } else {
-            oldBlock(bridge, index, json);
+            return oldBlock(bridge, index, json);
           }
         };
       }
@@ -408,9 +408,11 @@ void RCTParseObjCMethodName(NSString **objCMethodName, NSArray **arguments)
   // Set arguments
   NSUInteger index = 0;
   for (id json in arguments) {
-    id arg = RCTNilIfNull(json);
     RCTArgumentBlock block = _argumentBlocks[index];
-    block(bridge, index, arg);
+    if (!block(bridge, index, RCTNilIfNull(json))) {
+      // Invalid argument, abort
+      return;
+    }
     index++;
   }
 

React/Executors/RCTContextExecutor.m

@@ -558,7 +558,7 @@ static NSError *RCTNSErrorFromJSError(JSContextRef context, JSValueRef jsError)
   }), @"js_call,json_call", (@{@"objectName": objectName}))];
 }
 
-RCT_EXPORT_METHOD(setContextName:(NSString *)name)
+RCT_EXPORT_METHOD(setContextName:(nonnull NSString *)name)
 {
   if (JSGlobalContextSetName != NULL) {
     JSStringRef JSName = JSStringCreateWithCFString((__bridge CFStringRef)name);

React/Modules/RCTUIManager.m

@@ -820,6 +820,7 @@ RCT_EXPORT_METHOD(findSubviewIn:(nonnull NSNumber *)reactTag atPoint:(CGPoint)po
 - (void)batchDidComplete
 {
   RCTProfileBeginEvent();
+
   // Gather blocks to be executed now that all view hierarchy manipulations have
   // been completed (note that these may still take place before layout has finished)
   for (RCTComponentData *componentData in _componentDataByName.allValues) {
@@ -871,8 +872,13 @@ RCT_EXPORT_METHOD(findSubviewIn:(nonnull NSNumber *)reactTag atPoint:(CGPoint)po
   dispatch_async(dispatch_get_main_queue(), ^{
     RCTProfileEndFlowEvent();
     RCTProfileBeginEvent();
-    for (dispatch_block_t block in previousPendingUIBlocks) {
-      block();
+    @try {
+      for (dispatch_block_t block in previousPendingUIBlocks) {
+        block();
+      }
+    }
+    @catch (NSException *exception) {
+      RCTLogError(@"Exception thrown while executing UI block: %@", exception);
     }
     RCTProfileEndEvent(@"UIManager flushUIBlocks", @"objc_call", @{
       @"count": @(previousPendingUIBlocks.count),
@@ -1043,7 +1049,7 @@ RCT_EXPORT_METHOD(setMainScrollViewTag:(nonnull NSNumber *)reactTag)
         uiManager.mainScrollView = (id<RCTScrollableProtocol>)view;
         uiManager.mainScrollView.nativeMainScrollDelegate = uiManager.nativeMainScrollDelegate;
       } else {
-        RCTAssert(NO, @"Tag #%@ does not conform to RCTScrollableProtocol", reactTag);
+        RCTLogError(@"Tag #%@ does not conform to RCTScrollableProtocol", reactTag);
       }
     } else {
       uiManager.mainScrollView = nil;

React/Views/RCTWebViewManager.m

@@ -62,8 +62,9 @@ RCT_EXPORT_METHOD(goBack:(nonnull NSNumber *)reactTag)
     RCTWebView *view = viewRegistry[reactTag];
     if (![view isKindOfClass:[RCTWebView class]]) {
       RCTLogError(@"Invalid view returned from registry, expecting RCTWebView, got: %@", view);
+    } else {
+      [view goBack];
     }
-    [view goBack];
   }];
 }
 
@@ -73,8 +74,9 @@ RCT_EXPORT_METHOD(goForward:(nonnull NSNumber *)reactTag)
     id view = viewRegistry[reactTag];
     if (![view isKindOfClass:[RCTWebView class]]) {
       RCTLogError(@"Invalid view returned from registry, expecting RCTWebView, got: %@", view);
+    } else {
+      [view goForward];
     }
-    [view goForward];
   }];
 }
 
@@ -84,9 +86,10 @@ RCT_EXPORT_METHOD(reload:(nonnull NSNumber *)reactTag)
   [self.bridge.uiManager addUIBlock:^(__unused RCTUIManager *uiManager, RCTSparseArray *viewRegistry) {
     RCTWebView *view = viewRegistry[reactTag];
     if (![view isKindOfClass:[RCTWebView class]]) {
-      RCTLogMustFix(@"Invalid view returned from registry, expecting RCTWebView, got: %@", view);
+      RCTLogError(@"Invalid view returned from registry, expecting RCTWebView, got: %@", view);
+    } else {
+      [view reload];
     }
-    [view reload];
   }];
 }