Firebase crash report contains stack trace with <OR>

Question

I have an app in production and I'm using Firebase for error and crash logging. Lately, I've been seeing some lines in the stack trace of the exceptions, starting with <OR> . Below is an example taken directly (save for the package name) from an exception reported by Firebase:

Exception java.lang.NullPointerException: Attempt to invoke interface method 'void com.mycompany.myapp.managers.b$a.f()' on a null object reference
com.mycompany.myapp.managers.PermissionManager.getInstance (PermissionManager.java)
<OR>.checkPermission (PermissionManager.java)
<OR>.onRequestPermissionsResult (PermissionManager.java)
com.mycompany.myapp.activities.ShareImageActivity.onSaveShare (ShareImageActivity.java)
com.mycompany.myapp.activities.ShareImageActivity$3.onClick (ShareImageActivity.java)

I know that this is not a regular stack trace since onRequestPermissionResults does not call checkPermission and checkPermission does not call PermissionManager.getInstance . I assume this is one of the ways Android obfuscates the stack trace for the sake of security, but I couldn't find any documentation on this. Does anyone know how to interpret this stack trace?

Answer 1

The you see here is an indication that that Crash Reporting could not determine the actual object at that point. Currently, there is a known situation with Proguard deobfuscation where it could be ambiguous which object is the target here. This could be the case if you're stripping line numbers from your classes, which it looks like you are doing. This situation may improve if you are able to change your Proguard settings to remove the stripping of line numbers.

Answer 2

Add this to your proguard-rules.pro :

// obfuscate file name and keep line numbers
-renamesourcefileattribute SourceFile
-keepattributes SourceFile,LineNumberTable

It should remove ambiguity and you should not see <OR> in your stacktrace anymore.