Android: "FATAL EXCEPTION: mqt_js" / Error calling function: RCTDeviceEventEmitter:emit / - malformed JSON parsing in RN's android native code

Description

Calling fetch() and expecting JSON results (i.e. using response.json()) will crash if server sends malformed JSON. Error/logging system prints “Failed to create String from JSON:” and then does NOT print the JSON (the problem this ticket IS about).

https://github.com/facebook/react-native/issues/9117 promised to fix this, but did not.

Reproduction

Call fetch() and then response.json() with a server that returns bad JSON.

Additional Information

• React Native version: 0.36
• Platform: Android
• Operating System: MacOS

Here’s an example log:

11-04 13:39:46.611  3509  3509 D EPDG -- [EPDGService]: onDataActivity: direction=3
11-04 13:39:46.611  7541  7836 D NetworkController.MobileSignalController(0/2): onDataActivity: direction=3
11-04 13:39:46.781 17917 17917 V MediaPlayer-JNI: getCurrentPosition: 617 (msec)
11-04 13:39:47.031 17917 17917 V MediaPlayer-JNI: getCurrentPosition: 617 (msec)
11-04 13:39:47.281 17917 17917 V MediaPlayer-JNI: getCurrentPosition: 617 (msec)
11-04 13:39:47.541 17917 17917 V MediaPlayer-JNI: getCurrentPosition: 617 (msec)
11-04 13:39:47.641  3509  3509 D EPDG -- [EPDGService]: onDataActivity: direction=1
11-04 13:39:47.641  7541  7836 D NetworkController.MobileSignalController(0/2): onDataActivity: direction=1
11-04 13:39:47.791 17917 17917 V MediaPlayer-JNI: getCurrentPosition: 617 (msec)
11-04 13:39:47.821 17917 17976 I System.out: (HTTPLog)-Static: isSBSettingEnabled false
11-04 13:39:47.821 17917 17976 I System.out: (HTTPLog)-Static: isSBSettingEnabled false
11-04 13:39:47.821  3079  3883 D EnterpriseController: netId is 0
11-04 13:39:47.821  3079  3883 D Netd    : getNetworkForDns: using netid 507 for uid 10726
11-04 13:39:47.821 17917 17968 E AndroidRuntime: FATAL EXCEPTION: mqt_js
11-04 13:39:47.821 17917 17968 E AndroidRuntime: Process: com.stardust, PID: 17917
11-04 13:39:47.821 17917 17968 E AndroidRuntime: java.lang.RuntimeException: Error calling function: RCTDeviceEventEmitter:emit
11-04 13:39:47.821 17917 17968 E AndroidRuntime: 	at com.facebook.react.bridge.queue.NativeRunnable.run(Native Method)
11-04 13:39:47.821 17917 17968 E AndroidRuntime: 	at android.os.Handler.handleCallback(Handler.java:739)
11-04 13:39:47.821 17917 17968 E AndroidRuntime: 	at android.os.Handler.dispatchMessage(Handler.java:95)
11-04 13:39:47.821 17917 17968 E AndroidRuntime: 	at com.facebook.react.bridge.queue.MessageQueueThreadHandler.dispatchMessage(MessageQueueThreadHandler.java:31)
11-04 13:39:47.821 17917 17968 E AndroidRuntime: 	at android.os.Looper.loop(Looper.java:158)
11-04 13:39:47.821 17917 17968 E AndroidRuntime: 	at com.facebook.react.bridge.queue.MessageQueueThreadImpl$3.run(MessageQueueThreadImpl.java:196)
11-04 13:39:47.821 17917 17968 E AndroidRuntime: 	at java.lang.Thread.run(Thread.java:818)
11-04 13:39:47.821 17917 17968 E AndroidRuntime: Caused by: java.lang.RuntimeException: Failed to create String from JSON: 
11-04 13:39:47.821 17917 17968 E AndroidRuntime: 	... 7 more
11-04 13:39:47.841  3509  4040 W ActivityManager:   Force finishing activity com.stardust/.MainActivity
11-04 13:39:47.851  3509  4040 D FocusedStackFrame: Set to : 0
11-04 13:39:47.851  3509  4040 D InputDispatcher: Focused application set to: xxxx
11-04 13:39:47.861  3509  4040 D InputDispatcher: Focus left window: 17917
11-04 13:39:47.861  3509  3638 D PointerIcon: setMouseIconStyle1 pointerType: 1001 iconType:101 flag:0 pid:3509 uid:1000
11-04 13:39:47.861  3509  3638 D PointerIcon: setMouseCustomIcon IconType is same.101
11-04 13:39:47.931  3509 18371 E android.os.Debug: ro.product_ship = true
11-04 13:39:47.931  3509 18371 E android.os.Debug: ro.debug_level = 0x4f4c
11-04 13:39:47.931  3509 18371 E android.os.Debug: sys.mobilecare.preload = false
11-04 13:39:47.971  3509  3610 D ViewRootImpl: #1 mView = com.android.internal.policy.PhoneWindow$DecorView{5822614 V.E...... R.....I. 0,0-0,0}
11-04 13:39:47.981  3509  3610 D ISSUE_DEBUG: InputChannelName : 1cdbcb2 Application Error: com.stardust
11-04 13:39:47.981  3509  3610 V MARsPolicyManager: handelAlertToastWindowStarted pkgName = android
11-04 13:39:47.981  3509  3610 D InputDispatcher: Focus entered window: 3509
11-04 13:39:47.981  3509  3638 D PointerIcon: setMouseIconStyle1 pointerType: 1001 iconType:101 flag:0 pid:3509 uid:1000
11-04 13:39:47.981  3509  3638 D PointerIcon: setMouseCustomIcon IconType is same.101
11-04 13:39:47.991  3067  3067 I SurfaceFlinger: id=2946 createSurf (193x193),1 flag=4, ttardust
11-04 13:39:48.001 18372 18372 E Zygote  : v2
11-04 13:39:48.001 18372 18372 I libpersona: KNOX_SDCARD checking this for 1000
11-04 13:39:48.001  3509  3609 I ActivityManager: Start proc 18372:com.samsung.android.sm/1000 for broadcast-3 com.samsung.android.sm/.common.SmartManagerReceiver
11-04 13:39:48.001 18372 18372 I libpersona: KNOX_SDCARD not a persona

Questions:

• What do we have to do to actually include the JSON so we can get to the bottom of this?
• Why does it say “… 7 more” ?

[teyou]

it happens when I do

fetch('http://ideapit.net/filedata/201203/9fi32220120330230712.jpg')

and it’s only crash on Android release mode.

Hence, I switched to axios and since then no more crash!

[sammacbeth]

This expo app demonstrates the issue, and that the same code works on iOS: https://snack.expo.io/HJkNh3_Sz

Deeper analysis shows that the android network module retrieves the data and sends to the NativeEventEmitter: https://github.com/facebook/react-native/blob/3fc33bb54fc5dcf7ef696fe245addc320f85a269/ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkingModule.java#L390

It is then somewhere in the bridge code where the crash occurs. In the debugger I don’t get any further than here: https://github.com/facebook/react-native/blob/3fc33bb54fc5dcf7ef696fe245addc320f85a269/ReactAndroid/src/main/java/com/facebook/react/bridge/JavaScriptModuleRegistry.java#L91-L97

where the Java arguments are converted to a C++ object for the invocation of the bridged function. The crash stacktrace comes from the C++ jsc helper code: https://github.com/facebook/react-native/blob/3fc33bb54fc5dcf7ef696fe245addc320f85a269/ReactCommon/jschelpers/Value.cpp#L69-L77

As the crash is in the JS bridge, this bug could also affect other native modules which do not sanitise data before sending it to Javascript.