iOS 13 FirebaseDatabase crash inside safeHandleEvent

[adamup928]

On iOS 13, we're seeing crashes inside [FSRWebSocket safeHandleEvent:stream:] on line 1513.

I believe this crash occurs when returning to foreground, but can not say for sure.

• Xcode version: 11
  • Firebase SDK version: 6.9.0
  • Firebase Component: Database
  • Component version: resolves to 6.1.0 for cocoapod installation

# Cause: Crash due to signal: SIGBUS(BUS_ADRERR) at 1035b9a00

Thread 20 [Crashed]:

0    libdyld.dylib                            0x1afa5d6c0     dyld3::closure::ObjCStringTable::hash(char const*, unsigned long) const + 124
1    libdyld.dylib                            0x1afa5da6c     dyld3::closure::ObjCStringTable::getPotentialTarget(char const*) const + 20
2    libdyld.dylib                            0x1afa5dd40     dyld3::closure::ObjCClassDuplicatesOpt::getClassLocation(char const*, objc_opt::objc_opt_t const*, void*&) const + 44
3    libdyld.dylib                            0x1afa6a4bc     dyld3::AllImages::forEachObjCClass(char const*, void (void*, bool, bool*) block_pointer) const + 72
4    libobjc.A.dylib                          0x1af99cc38     getPreoptimizedClass + 148
5    libobjc.A.dylib                          0x1af9878d8     getClassExceptSomeSwift(char const*) + 20
6    libobjc.A.dylib                          0x1af988784     look_up_class + 100
7    CoreFoundation                           0x1afb586f8     -[__NSCFError copyWithZone:] + 36
8    [redacted]                            0x102f9ddcc     -[FSRWebSocket safeHandleEvent:stream:] (FSRWebSocket.m:1513)
9    [redacted]                            0x102f9dc34     _35-[FSRWebSocket stream:handleEvent:]_block_invoke.380 (FSRWebSocket.m:1488)
10   libdispatch.dylib                        0x1af925610     _dispatch_call_block_and_release + 24
11   libdispatch.dylib                        0x1af926184     _dispatch_client_callout + 16
12   libdispatch.dylib                        0x1af90373c     _dispatch_lane_serial_drain$VARIANT$armv81 + 564
13   libdispatch.dylib                        0x1af904154     _dispatch_lane_invoke$VARIANT$armv81 + 400
14   libdispatch.dylib                        0x1af90d43c     _dispatch_workloop_worker_thread + 576
15   libsystem_pthread.dylib                  0x1af975fa4     _pthread_wqthread + 276
16   libsystem_pthread.dylib                  0x1af978ae0     start_wqthread + 8

[paulb777]

A quick workaround for the crash would be to comment out line 1513, since the crash occurs doing a copy for a disabled log.

We should get a better understanding of this though.

[adamup928]

Thanks for the fast response, @paulb777. We'll do that for now and monitor for updates.