How do you troubleshoot an Android system library crash (libwebcore.so)

Question

My Android webview is crashing and the error dump from adb logcat tells me that libwebcore.so is the library causing the segmentation fault. How do you troubleshoot this?

My initial research took me to places like this thread: How to use addr2line in Android, which in essence says to get the non-stripped version of the library and use the addr2line utility to pinpoint the exact line causing the segmentation fault

The thread above says "Use the .so file under obj/local/armeabi, since this is the non-stripped version"...but I couldn't find libwebcore.so anywhere under /usr/local/android-ndk-r6 or /usr/local/android-sdk-mac_86 on my Mac, and I only found a stripped version of libwebcore.so under /system/lib on the Android device.

Is there a way I can get my hands on a non-stripped version of libwebcore.so? Or am I just not going about this the right way?

---

For reference, here is the error dump as spit out by adb logcat:

I/DEBUG   (   65): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
I/DEBUG   (   65): Build fingerprint: 'google/passion/passion:2.3.4/GRJ22/121341:user/release-keys'
I/DEBUG   (   65): pid: 611, tid: 618  >>> com.swishly.gap <<<
I/DEBUG   (   65): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 00000000
I/DEBUG   (   65):  r0 00000002  r1 002f9564  r2 00000003  r3 008e79c8
I/DEBUG   (   65):  r4 00000000  r5 002f9700  r6 00000000  r7 4470baf4
I/DEBUG   (   65):  r8 4470bb64  r9 44520ea8  10 002ae048  fp 00000000
I/DEBUG   (   65):  ip 00000000  sp 4470bad0  lr a851857b  pc a851838e  cpsr 00000030
I/DEBUG   (   65):  d0  0061006300000000  d1  0064006500680000
I/DEBUG   (   65):  d2  0077007400650000  d3  004c006b00720000
I/DEBUG   (   65):  d4  007400610063006f  d5  0053006e006f0069
I/DEBUG   (   65):  d6  006300720075006f  d7  0000000000000065
I/DEBUG   (   65):  d8  0000000000000000  d9  0000000000000000
I/DEBUG   (   65):  d10 0000000000000000  d11 0000000000000000
I/DEBUG   (   65):  d12 0000000000000000  d13 0000000000000000
I/DEBUG   (   65):  d14 0000000000000000  d15 0000000000000000
I/DEBUG   (   65):  d16 41d39d979893f080  d17 41d39d9b0a07ff06
I/DEBUG   (   65):  d18 41106a1000000000  d19 4024000000000000
I/DEBUG   (   65):  d20 0000000000000000  d21 0000000000000000
I/DEBUG   (   65):  d22 4024000000000000  d23 0000000000000000
I/DEBUG   (   65):  d24 0000000000000000  d25 3ff0000000000000
I/DEBUG   (   65):  d26 0000000000000000  d27 bff0000000000000
I/DEBUG   (   65):  d28 0000000000000000  d29 3ff0000000000000
I/DEBUG   (   65):  d30 0000000000000000  d31 3ff0000000000000
I/DEBUG   (   65):  scr 20000013
I/DEBUG   (   65): 
I/DEBUG   (   65):          #00  pc 0021838e  /system/lib/libwebcore.so
I/DEBUG   (   65):          #01  pc 00218576  /system/lib/libwebcore.so
I/DEBUG   (   65):          #02  pc 002186f8  /system/lib/libwebcore.so
I/DEBUG   (   65):          #03  pc 0021873a  /system/lib/libwebcore.so
I/DEBUG   (   65):          #04  pc 0021875c  /system/lib/libwebcore.so
I/DEBUG   (   65):          #05  pc 0021879a  /system/lib/libwebcore.so
I/DEBUG   (   65):          #06  pc 0021febe  /system/lib/libwebcore.so
I/DEBUG   (   65):          #07  pc 00220df0  /system/lib/libwebcore.so
I/DEBUG   (   65):          #08  pc 0022147c  /system/lib/libwebcore.so
I/DEBUG   (   65):          #09  pc 00017e34  /system/lib/libdvm.so
I/DEBUG   (   65): 
I/DEBUG   (   65): code around pc:
I/DEBUG   (   65): a851836c 602303c2 eb03e002 602003c2 46206063 
I/DEBUG   (   65): a851837c bf00bd70 b510680b b1134604 1c426818 
I/DEBUG   (   65): a851838c 6820601a f7ff6023 4620fd55 bf00bd10 
I/DEBUG   (   65): a851839c 4604b510 fd1ef7ff f6534620 4620fa73 
I/DEBUG   (   65): a85183ac bf00bd10 4604b570 460e6cc0 f6acb168 
I/DEBUG   (   65): 
I/DEBUG   (   65): code around lr:
I/DEBUG   (   65): a8518558 d10242a5 2600462c 6823e017 f1b3b113 
I/DEBUG   (   65): a8518568 d1f83fff e7f33408 1d216878 f7ff1980 
I/DEBUG   (   65): a8518578 3408ff03 d00642a5 2b006823 f1b3d0f9 
I/DEBUG   (   65): a8518588 d1013fff 462ce7f5 42ac3604 e8bdd1ec 
I/DEBUG   (   65): a8518598 bf0081f0 b087b5f0 0710f100 4604ae03 
I/DEBUG   (   65): 
I/DEBUG   (   65): stack:
I/DEBUG   (   65):     4470ba90  00953a1c  
I/DEBUG   (   65):     4470ba94  a83da669  /system/lib/libwebcore.so
I/DEBUG   (   65):     4470ba98  9de0413c  
I/DEBUG   (   65):     4470ba9c  00000001  
I/DEBUG   (   65):     4470baa0  00953a18  
I/DEBUG   (   65):     4470baa4  0000a000  
I/DEBUG   (   65):     4470baa8  4470bb64  
I/DEBUG   (   65):     4470baac  44520ea8  
I/DEBUG   (   65):     4470bab0  002ae048  
I/DEBUG   (   65):     4470bab4  afd1362d  /system/lib/libc.so
I/DEBUG   (   65):     4470bab8  4470baf4  
I/DEBUG   (   65):     4470babc  00953a1c

Dynode

have you tried checking why your WebView is causing libwebcore.so crash? I don't think there can be a major bug in system libraries. – Equiangular

here is a link to the WebView source code that actually loads the webcore native library. I suggest you try to narrow down which native method in there would produce the crash? – Shankle

Answer 1

You can checkout the whole WebKit xcode project along with the whole Android open source project with the link Kerubu provided (I did a few months ago, it takes multiple gigabytes & hours...) and probably create your own unstripped .so library (I didn't), but I doubt this is the easiest way to take on this issue.

Edit: it turns out android is mirrored on github, here's the WebCore project.

There is a good chance that your application is far easier to troubleshoot than the WebKit project!

I'll allow myself to throw a wild guess:

There are known bugs with javascript injection (also here) for some devices only that seem to be affecting some html app framework as well (such as PhoneGap, apparently), do you use the method addJavascriptInterface? If so there is a workaround, calling the WebChromeClient's onJsPrompt and parsing the string to perform native calls from the webview.

Java to javascript:

webview.loadUrl("javascript:alert('toto');");

javascript to java:

in javascript:

prompt('this is the message', 'this is the default value');

and in java:

WebChromeClient chromeClient = new WebChromeClient(){
  @Override
  public boolean onJsPrompt(WebView view, String url, String message, String defaultValue, android.webkit.JsPromptResult result){
      Log.d("javascriptPrompt", "prompt : "+url+"-"+message);
      // should log "javascriptPrompt, "prompt: null - this is the message"
      // parse the message and do whatever you want here
      result.confirm();
      return true;
  }
}
webview.setChromeClient(chromeClient);

Shankle

Thanks Thomas, I think you're right: I was hoping a libwebcore stack trace would provide some clues because the circumstances of the crash are pretty hard to track, but this looks like a lot'o pain for very little gain. On the other hand, my app does javascript injection so thanks a lot for providing these links – Dynode

Answer 2

Not 100% sure but is the source for libwebkit.so to be found in Android Open Source Project?

Herisau