Debugging an Android crash without a stack trace

Question

This app instantiates a WebView on app launch without adding it to the UI tree. This is done for preloading purposes.

When finally adding the WebView to the UI tree later on, the app crashes without a stack trace.

At the time the WebView gets added to the UI tree, logcat shows the following on an emulator running API level 22:

D <last app event before adding preloaded webview to ui tree>
W ResourceType: No known package when getting name for resource number 0xffffffff
E eglCodecCommon: glUtilsParamSize: unknow param 0x000085b5
E eglCodecCommon: glUtilsParamSize: unknow param 0x00008b49
E eglCodecCommon: glUtilsParamSize: unknow param 0x00008b4b
E eglCodecCommon: glUtilsParamSize: unknow param 0x00008b4a
D AndroidRuntime: >>>>>> START com.android.internal.os.RuntimeInit uid 10059 <<<<<<
D AndroidRuntime: CheckJNI is ON
E cutils-trace: Error opening trace file: Permission denied (13)
E memtrack: Couldn't load memtrack module (No such file or directory)
E android.os.Debug: failed to load memtrack module: -2
D AndroidRuntime: Calling main entry org.chromium.components.crash.browser.CrashpadMain
W linker  : libwebviewchromium.so: unused DT entry: type 0x6ffffef5 arg 0x4c34
W linker  : libwebviewchromium.so: unused DT entry: type 0x6ffffffe arg 0x4bd4
W linker  : libwebviewchromium.so: unused DT entry: type 0x6fffffff arg 0x3
E chromium: [0722/152535.383241:ERROR:elf_dynamic_array_reader.h(61)] tag not found
E chromium: [0722/152535.394807:ERROR:file_io_posix.cc(140)] open /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq: No such file or directory (2)
E chromium: [0722/152535.394897:ERROR:file_io_posix.cc(140)] open /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq: No such file or directory (2)
E chromium: [0722/152535.401624:ERROR:system_snapshot_linux.cc(125)] Couldn't read property ro.product.board
D AndroidRuntime: Shutting down VM
I WindowState: WIN DEATH: Window{2507ca0c u0 com.myapp.debug}

Does this point to the root cause of the crash?

I'm wondering if they are instead part of a crash recovery/dump mechanism (due to the reference to "CrashpadMain" before the errors), and if I would be able to find a stack trace elsewhere. While I can use adb bugreport, I don't know where to look in the report for information on the crash instance.

Of note, I've only been able to reproduce this crash (though consistently) on emulators, and only running API levels 22, 25, 27 and 29. A physical device, and an emulator running API level 23, do not reproduce it.

Answer 1

From the crash output it looks like the builds you're using have is_official_build=true set? (which makes sense for perf I guess) This basically prevents Android from generating useful crash dump output at all, because the unwind tables are omitted from the binary. The only way to debug crashes in this kind of binary is to use Crashpad dumps, but those are unlikely to be hooked up usefully in a test environment?

Build with exclude_unwind_tables=false to override the default. This will increase binary size quite a bit, but should result in you getting a meaningful stack backtrace with more than one frame. You should then be able to symbolise the stack trace addresses to find out what's crashing.

exclude_unwind_tables Current value (from the default) = true From //build/config/compiler/compiler.gni:103

Exclude unwind tables by default for official builds as unwinding can be
done from stack dumps produced by Crashpad at a later time "offline" in the
crash server. Since this increases binary size, we don't recommend including
them in shipping builds.
For unofficial (e.g. development) builds and non-Chrome branded (e.g. Cronet
which doesn't use Crashpad, crbug.com/479283) builds it's useful to be able
to unwind at runtime.