App Crash in CFNetwork appWasLaunchedForBackgroundSession

App & System Services Core OS
bpsym OP
Created Oct ’20
Replies 7
Boosts 0
Views 1.5k
Participants 3
We've started to see thousands of crashes on iOS 14.0 (a few on iOS 14.2) when our app is launched for a background session. It looks like CFNetwork is logging something.

Is this a bug in CFNetwork? Has anyone encountered a similar crash?

Code Block language
Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Subtype: KERN_INVALID_ADDRESS at 0x0000000d466bbe9c
VM Region Info: 0xd466bbe9c is not in any region.  Bytes after previous region: 45741751965  Bytes before following region: 10629693796
      REGION TYPE                      START - END             [ VSIZE] PRT/MAX SHRMOD  REGION DETAIL
      MALLOC_NANO                   280000000-2a0000000        [512.0M] rw-/rwx SM=PRV  
--->  GAP OF 0xd20000000 BYTES
      commpage (reserved)           fc0000000-1000000000       [  1.0G] ---/--- SM=NUL  ...(unallocated)
Termination Signal: Segmentation fault: 11
Termination Reason: Namespace SIGNAL, Code 0xb
Terminating Process: exc handler [202]
Triggered by Thread:  0
Thread 0 name:
Thread 0 Crashed:
0   libobjc.A.dylib               	0x000000019422b1c0 objc_opt_isKindOfClass + 20 (objc-object.h:260)
1   libsystem_trace.dylib         	0x0000000195dd60a4 _os_log_fmt_flatten_object + 816 (format.m:109)
2   libsystem_trace.dylib         	0x0000000195de2500 _os_log_impl_flatten_and_send + 1716 (format.c:799)
3   libsystem_trace.dylib         	0x0000000195de1e34 _os_log + 152 (log.c:2214)
4   libsystem_trace.dylib         	0x0000000195de45e0 _os_log_impl + 12 (log.c:2228)
5   CFNetwork                     	0x0000000181078dd0 -[NSURLBackgroundSession appWasLaunchedForBackgroundSession:] + 240 (BackgroundSession.mm:0)
6   CoreFoundation                	0x0000000180949098 CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER + 20 (CFNotificationCenter.c:706)
7   CoreFoundation                	0x0000000180949058 _CFXRegistrationPost_block_invoke + 48 (CFNotificationCenter.c:173)
8   CoreFoundation                	0x0000000180948650 _CFXRegistrationPost + 400 (CFNotificationCenter.c:198)
9   CoreFoundation                	0x0000000180948048 _CFXNotificationPost + 696 (CFNotificationCenter.c:1071)
10  Foundation                    	0x0000000181b67b20 -[NSNotificationCenter postNotificationName:object:userInfo:] + 60 (NSNotification.m:575)
11  CFNetwork                     	0x000000018117bd40 +[NSURLSession _sendPendingCallbacksForSessionIdentifier:] + 64 (Session.mm:222)
12  UIKitCore                     	0x000000018323e990 -[UIApplication _handleNonLaunchSpecificActions:forScene:withTransitionContext:completion:] + 2932 (UIApplication.m:10283)
13  UIKitCore                     	0x0000000182750538 -[UIScene _emitSceneSettingsUpdateResponseForCompletion:afterSceneUpdateWork:] + 476 (UIScene.m:1118)
14  UIKitCore                     	0x0000000182751600 -[UIScene scene:didUpdateWithDiff:transitionContext:completion:] + 220 (UIScene.m:1380)
15  UIKitCore                     	0x0000000182d6ad84 -[UIApplicationSceneClientAgent scene:handleEvent:withCompletion:] + 464 (UIApplicationSceneClientAgent.m:80)
16  FrontBoardServices            	0x000000018f2654b0 -[FBSScene updater:didUpdateSettings:withDiff:transitionContext:completion:] + 456 (FBSScene.m:547)
17  FrontBoardServices            	0x000000018f28dcec 94-[FBSWorkspaceScenesClient _queue_updateScene:withSettings:diff:transitionContext:completion:]_block_invoke_2 + 124 (FBSWorkspaceScenesClient.m:533)
18  FrontBoardServices            	0x000000018f272410 -[FBSWorkspace _calloutQueue_executeCalloutFromSource:withBlock:] + 232 (FBSWorkspace.m:355)
19  FrontBoardServices            	0x000000018f28dc38 94-[FBSWorkspaceScenesClient _queue_updateScene:withSettings:diff:transitionContext:completion:]_block_invoke + 368 (FBSWorkspaceScenesClient.m:532)
20  libdispatch.dylib             	0x000000018061f280 _dispatch_client_callout + 16 (object.m:559)
21  libdispatch.dylib             	0x00000001805c4b0c _dispatch_block_invoke_direct$VARIANT$mp + 224 (queue.c:468)
22  FrontBoardServices            	0x000000018f2b14b8 FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK + 40 (FBSSerialQueue.m:184)
23  FrontBoardServices            	0x000000018f2b1180 -[FBSSerialQueue _targetQueue_performNextIfPossible] + 404 (FBSSerialQueue.m:227)
24  FrontBoardServices            	0x000000018f2b1654 -[FBSSerialQueue _performNextFromRunLoopSource] + 28 (FBSSerialQueue.m:258)
25  CoreFoundation                	0x0000000180966240 CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION + 24 (CFRunLoop.c:1967)
26  CoreFoundation                	0x0000000180966140 CFRunLoopDoSource0 + 204 (CFRunLoop.c:2011)
27  CoreFoundation                	0x0000000180965488 CFRunLoopDoSources0 + 256 (CFRunLoop.c:2048)
28  CoreFoundation                	0x000000018095fa40 __CFRunLoopRun + 776 (CFRunLoop.c:2925)
29  CoreFoundation                	0x000000018095f200 CFRunLoopRunSpecific + 572 (CFRunLoop.c:3242)
30  GraphicsServices              	0x0000000196a5a598 GSEventRunModal + 160 (GSEvent.c:2259)
31  UIKitCore                     	0x0000000183225004 -[UIApplication _run] + 1052 (UIApplication.m:3270)
32  UIKitCore                     	0x000000018322a5d8 UIApplicationMain + 164 (UIApplication.m:4739)
33  <app>          	0x00000001004853a4 main + 68 (AppDelegate.swift:26)
34  libdyld.dylib                 	0x000000018063e598 start + 4


Replies  7
Boosts  0
Views  1.5k
Participants  3
DTS Engineer OP
Apple
Oct ’20
Hmmm, that doesn’t look good.

Is this a bug in CFNetwork?

Quite possibly. It’s definitely worth you filing a bug report about it. Please post your bug number, just for the record.

Has anyone encountered a similar crash?

Hard to say without seeing the full crash report. Can you post it here? Please use the text attachment syntax to minimise the impact on the timeline.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@apple.com"
0
bpsym OP
Oct ’20
Thanks! Filed FB8779823 and attached some full crash logs to it.
0
DTS Engineer OP
Apple
Oct ’20

Filed FB8779823 and attached some full crash logs to it.

Thanks for that. Based on your crash reports it seems that this crash is affecting a wide range of apps, which suggests that it’s not your code but rather a problem with the system itself.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@apple.com"
0
SanY OP
Dec ’20
Hey,
Did you get any resolution for this? i'm facing the exact same issue in my app, with exact crash logs line-by-line.
0
DTS Engineer OP
Apple
Dec ’20
Are you still seeing this on 14.3? Looking at the bug there’s some suggestion that this was fixed there.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@apple.com"
0
SanY OP
Jan ’21
Yes, i'm still seeing this in 14.3. Checked Firebase and confirmed it.
0
bpsym OP
Jan ’21
Thanks, Eskimo. From my side, I no longer see these crashes in 14.3, only 14.2 and below.
0
App Crash in CFNetwork appWasLaunchedForBackgroundSession
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