iOS 13 Background Crash in GoogleDataTransport

[adamup928]

On iOS 13, we're seeing unpredictable crashes inside GoogleDataTransport when our app goes to the background.

• Xcode version: 11.0
• Firebase SDK version: 6.8.1
• Firebase Component: Core
• Component version: FirebaseCoreDiagnostics 1.0.1; GoogleDataTransport 1.2.0

Crash log & relevant backtrace:

data:text/text;charset=utf-8,
# Cause: Crash due to signal: SIGBUS(BUS_ADRERR) at 102ee0149
# Reported at: 2019-09-20 17:06:52 UTC

Thread 0 [Crashed]:

0    libdyld.dylib                            0x1c30c0244     dyld3::closure::Image::containsAddress(void const*, void const*, unsigned char*) const + 148
1    libdyld.dylib                            0x1c30cae10     dyld3::AllImages::immutableMemory(void const*, unsigned long) const + 40
2    libdyld.dylib                            0x1c30cad04     __ZNK5dyld39AllImages20infoForImageMappedAtEPKvPPKNS_11MachOLoadedEPyPPKc_block_invoke.35 + 40
3    libdyld.dylib                            0x1c30caa48     dyld3::AllImages::infoForImageMappedAt(void const*, dyld3::MachOLoaded const**, unsigned long long*, char const**) const + 468
4    libdyld.dylib                            0x1c30cf2d8     dyld3::dladdr(void const*, dl_info*) + 184
5    libdyld.dylib                            0x1c30c32d4     dladdr + 204
6    UIKitCore                                0x1c72e74f8     _86-[UIApplication(UIAlternateApplicationIcons) _setAlternateIconName:completionHandler:]_block_invoke_4 + 8
7    UIKitCore                                0x1c72e7ae0     __UIAdaptLocalizedStringForView_block_invoke + 184
8    <redacted>                            0x102b678ec     -[GDTApplication beginBackgroundTaskWithExpirationHandler:] (GDTPlatform.m:106)
9    <redacted>                            0x102b6b184     -[GDTTransformer appWillBackground:] (GDTTransformer.m:92)
10   <redacted>                            0x102b6714c     -[GDTLifecycle applicationDidEnterBackground:] (GDTLifecycle.m:74)
11   CoreFoundation                           0x1c321809c     _CFXNotificationPostToken + 292
12   CoreFoundation                           0x1c32180e4     _CFXNotificationPostToken + 364
13   CoreFoundation                           0x1c3217444     _CFXNotificationTokenRegistrationCopyObserver + 24
14   CoreFoundation                           0x1c32170fc     _CFXRegistrationPost2 + 32
15   CoreFoundation                           0x1c319343c     -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 636
16   CoreFoundation                           0x1c3216a4c     _CFXNotificationPost + 704
17   Foundation                               0x1c35732d8     -[NSProcessInfo _registerForHardwareStateNotifications] + 88
18   <redacted>                            0x102b67ad0     -[GDTApplication iOSApplicationDidEnterBackground:] (GDTPlatform.m:153)
19   CoreFoundation                           0x1c321809c     _CFXNotificationPostToken + 292
20   CoreFoundation                           0x1c32180e4     _CFXNotificationPostToken + 364
21   CoreFoundation                           0x1c3217444     _CFXNotificationTokenRegistrationCopyObserver + 24
22   CoreFoundation                           0x1c32170fc     _CFXRegistrationPost2 + 32
23   CoreFoundation                           0x1c319343c     -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 636
24   CoreFoundation                           0x1c3216a4c     _CFXNotificationPost + 704
25   Foundation                               0x1c35732d8     -[NSProcessInfo _registerForHardwareStateNotifications] + 88
26   UIKitCore                                0x1c72cf0ec     _65-[UIApplication _beginSnapshotSessionForScene:withSnapshotBlock:]_block_invoke_2 + 24
27   UIKitCore                                0x1c6cca284     -[UIViewController _presentViewController:withAnimationController:completion:] + 3736
28   UIKitCore                                0x1c72ceea8     _65-[UIApplication _beginSnapshotSessionForScene:withSnapshotBlock:]_block_invoke + 0
29   UIKitCore                                0x1c6aa4c88     -[_UIWindowSceneDeviceOrientationSettingsDiffAction _performActionsForUIScene:withUpdatedFBSScene:settingsDiff:fromSettings:transitionContext:lifecycleActionType:] + 456
30   UIKitCore                                0x1c6f348a8     -[_UIPathLazyImageAsset _containsImagesInPath:] + 60
31   UIKitCore                                0x1c6aa4864     -[_UISceneScreenBasedMetricsCalculator _setScene:] + 0
32   UIKitCore                                0x1c6aa42bc     -[_UIScenefbsSceneBasedMetricsCalculator _updateMetricsOnWindows:animated:] + 400
33   UIKitCore                                0x1c6aa4690     -[_UISceneScreenBasedMetricsCalculator _updateMetricsOnWindows:animated:] + 348
34   UIKitCore                                0x1c6aa3f4c     _69-[_UISceneLifecycleMultiplexer _prepareForClientSuspensionWithScene:]_block_invoke + 52
35   UIKitCore                                0x1c6918c0c     -[UIScene _topVisibleWindowPassingTest:] + 208
36   UIKitCore                                0x1c74f20b4     -[UILayoutManagerBasedDraggableGeometry textRangesForAttachmentsInTextRange:] + 56
37   UIKitCore                                0x1c72c5ebc     -[UIApplication _pushRunLoopMode:requester:reason:] + 528
38   UIKitCore                                0x1c6e880f4     +[NSURL(UIKitAdditions) mapsURLWithSourceAddress:destinationAddress:] + 320
39   FrontBoardServices                       0x1c8354bdc     -[FBSSceneImpl _callOutQueue_agent_willDestroyWithTransitionContext:completion:] + 436
40   FrontBoardServices                       0x1c837ab70     _84-[FBSWorkspaceScenesClient _queue_invalidateScene:withTransitionContext:completion:]_block_invoke_2 + 64
41   FrontBoardServices                       0x1c835f0f8     -[FBSWorkspace _calloutQueue_executeCalloutFromSource:withBlock:] + 196
42   FrontBoardServices                       0x1c837a9e8     _84-[FBSWorkspaceScenesClient _queue_invalidateScene:withTransitionContext:completion:]_block_invoke + 244
43   libdispatch.dylib                        0x1c2f8a184     _dispatch_client_callout + 16
44   libdispatch.dylib                        0x1c2f33038     _dispatch_block_invoke_direct$VARIANT$mp + 224
45   FrontBoardServices                       0x1c839e540     _FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 4
46   FrontBoardServices                       0x1c839e20c     -[FBSSerialQueue _queue_performNextIfPossible] + 368
47   FrontBoardServices                       0x1c839e734     _73-[FBSSerialQueue _setSynchronizingEnqueueSemaphore:forWorkspaceWithName:]_block_invoke + 292
48   CoreFoundation                           0x1c323a7e0     _CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 8
49   CoreFoundation                           0x1c323a738     _CFRunLoopDoSource1 + 404

[adamup928]

Possibly related: #3759

Also maybe related, we're seeing background fetch watchdog timer violations that cause crashes. Our application does not have backgroundFetch entitlements. Most of the time, crash logs are not generated. Here's a sample of the related console logs from a SysDiagnose:

[application<redacted>:1038] Terminating with context: <RBSTerminateContext: 0x102c77180; code: 0x2182BAAD; explanation: "Timed-out waiting for process [daemon<com.apple.dasd>:123] to invalidate assertion with identifier 25-123-11503 and explanation 'com.apple.das.backgroundFetch'. Direct this report to owners of that process"; reportType: 0; maxRole: 7; maxTerminationResistance: 3>

[ryanwilson]

@adamup928 thank you for the report and sorry you're seeing these troubles. We're taking a look and will try to figure out what's going on ASAP.

[mikehaney24]

We're working on a fix for this--the slowdown is due to Firebase's yearly summit.

[adamup928]

@mikehaney24 - thanks! I appreciate the update.

[adamup928]

Just wanted to update here that the crashes still occur with Firebase 6.9.0.

Notes:

1. No crash report is generated, even on the device.
2. Inspecting the SysDiagnose logs reveals the following statement preceding every crash:

Process exited: <FBApplicationProcess: 0x112356270; application<[redacted]>:9206> -> <RBSProcessExitContext; specific: <RBSProcessExitStatus; domain: runningboard (15); code: 0x2182baad>; terminationContext: <RBSTerminateContext: 0x282e6b780; code: 0x2182BAAD; explanation: "Timed-out waiting for process [application<[redacted]>:9206] to invalidate assertion with identifier 27-9206-95179 and explanation 'Shared Background Assertion 142 for [redacted]'. Direct this report to owners of that process"; reportType: 0; maxRole: 7; maxTerminationResistance: 3>>

3. We have no background fetch operations in our application.

[elrodsj]

I'm seeing the same as @adamup928. I do not have background operations in my app either.