Unity Android signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x0

Question

I'm building an Android App with Unity 2018.1.0f2 and get some kind of segmentation fault while running it. The exact error is the following:

05-16 20:54:11.834: E/SamsungIME(9413): <AbstractKeyboardView> - onDraw() called
05-16 20:54:12.142: E/ViewRootImpl(17850): sendUserActionEvent() mView == null
05-16 20:54:12.146: E/SKBD KeyboardInfoUtils(9413): getInstance start
05-16 20:54:12.146: E/SKBD KeyboardInfoUtils(9413): sendSIPInformation state:6  isAbstractKeyboardView : true
05-16 20:54:12.151: E/SKBD KeyboardInfoUtils(9413): sending null keyboardInfo as SIP is closed
05-16 20:54:15.401: A/libc(17850): Fatal signal 11 (SIGSEGV), code 1, fault addr 0x0 in tid 17865 (UnityMain)
05-16 20:54:15.401: A/libc(17850): [ 05-16 20:54:15.407  3096: 3096 W/         ]
05-16 20:54:15.401: A/libc(17850): debuggerd: handling request: pid=17850 uid=10350 gid=10350 tid=17865
05-16 20:54:15.633: A/DEBUG(17987): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
05-16 20:54:15.634: A/DEBUG(17987): Build fingerprint: 'samsung/heroltexx/herolte:7.0/NRD90M/G930FXXS2DRDI:user/release-keys'
05-16 20:54:15.635: A/DEBUG(17987): Revision: '8'
05-16 20:54:15.635: A/DEBUG(17987): ABI: 'arm'
05-16 20:54:15.635: A/DEBUG(17987): pid: 17850, tid: 17865, name: UnityMain  >>> de.zoomapp.zoom <<<
05-16 20:54:15.635: A/DEBUG(17987): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x0
05-16 20:54:15.636: A/DEBUG(17987):     r0 00000000  r1 c7ad20b0  r2 cf9ffc24  r3 efc62308
05-16 20:54:15.637: A/DEBUG(17987):     r4 c7ad20b0  r5 c7ad20cc  r6 ffffffff  r7 00000000
05-16 20:54:15.637: A/DEBUG(17987):     r8 00000000  r9 ee67ecb4  sl ee67ebc8  fp ee67e5e8
05-16 20:54:15.637: A/DEBUG(17987):     ip c7ad20b0  sp ee67e5c8  lr cf9ffc3c  pc f2386338  cpsr a00e0030
05-16 20:54:15.651: A/DEBUG(17987): backtrace:
05-16 20:54:15.652: A/DEBUG(17987):     #00 pc 00018338  /system/lib/libc.so (strcmp+47)
05-16 20:54:15.652: A/DEBUG(17987):     #01 pc 0014bc38  /data/app/de.zoomapp.zoom-1/lib/arm/libunity.so
05-16 20:54:15.652: A/DEBUG(17987):     #02 pc 00008484  <anonymous:c7275000>
05-16 20:54:17.518: E/audit(4645): type=1701 audit(1526496857.505:4791): auid=4294967295 uid=10350 gid=10350 ses=4294967295 subj=u:r:untrusted_app:s0:c512,c768 pid=17865 comm="UnityMain" exe="/system/bin/app_process32" sig=11
05-16 20:54:17.562: E/lowmemorykiller(3180): Error writing /proc/17850/oom_score_adj; errno=22

I try to provide each screen in landscape and portrait mode. When the user is in the login screen and clicks the login button, a UnityWebRequest is sent to the server. If the server responds with a positive result, the UI transitions opens a loading screen, in the background multiple UnityWebRequests are sent to retrieve more information about icons and images to show. When loading is done the main menu is shown and in the background the game is already loaded, but paused. This game consists of only showing a bunch of images and is pretty static, which is the reason why I don't describe it in detail here. The said crash occurs, if the user rotates his phone from portrait to landscape right after clicking login and while the loading screen shows. I could reproduce this error all the time on my Samsung Galaxy S7, but could not make a minimal example in a clean project. It might be a problem with yielding the web requests maybe? I put log messages all over my code and before the crash I often saw the yield statement of some web request. I have more coroutines loading some images in async. If I comment out all coroutines it runs fine, but I don't know if this is due to the loading running very fast or if coroutines cause the problem. I then searched on the internet and found to use addr2line tool. It produced for the address 0014bc38:

operator delete[](void*, std::nothrow_t const&)

I can't find the exact problem. I hope maybe someone has a hint how I can search for this. Thank you guys.

Regards, Michael

Answer 1

SEG_MAPERR with address of 0x0 is null pointer dereference.

It's valid to delete a null pointer (and should be for the delete[] operator). I suspect that you have some sort of race condition. Put some logs when you delete or free anything (although everything is GC...)

Also, check the official bug tracker and submit a new bug if you can't find something similar. I suspect that it is trying to access a null pointer when the new window parameters are sent to the app.