How to diagnose a crash that appears to be internal to WebCore (Thread 2, SIGSEGV)

Hello esteemed SO'ers,

A crash recently popped up that's perplexing me. It occurs on Thread 2, appears to be internal to WebCore, is Exception Type SIGSEGV and Exception Code SEGV_ACCERR. Full crash log below.

The App uses UIWebViews throughout. The main WebView displays roughly 30 images that reside on disk, and uses a custom NSURLProtocol to pass messages between native and JavaScript and vice versa.

I'm hoping someone can help me better understand crashes like this (ones that don't point to a particular class/method/line in my code, seem to be inside Apple classes) and how to approach diagnosing and fixing them.

I've read up on SIGSEGV and have Googled many variations of info from the crash report. Haven't found anything too helpful yet. Thanks in advance for any pointers.

Incident Identifier: [TODO]  
CrashReporter Key:   [TODO]  
Hardware Model:      iPad3,6  
Process:         CurrentTarget [56978]  
Path:            /var/mobile/Applications/XXXXXXX-5392-49F5-99AE-XXXXXXXXXXX/CurrentTarget.app/CurrentTarget  
Identifier:      com.xxx.xxxxxxx  
Version:         1.10.7  
Code Type:       ARM  
Parent Process:  launchd [1]  


Date/Time:       2013-07-05 14:38:02 +0000  
OS Version:      iPhone OS 6.1.3 (10B329)  
Report Version:  104  


Exception Type:  SIGSEGV  
Exception Codes: SEGV_ACCERR at 0x4  
Crashed Thread:  2  


Thread 0:  
0   libsystem_kernel.dylib              0x3b67ce30 mach_msg_trap + 20  
1   CoreFoundation                      0x332d42bb __CFRunLoopServiceMachPort + 131  
2   CoreFoundation                      0x332d2fdb __CFRunLoopRun + 819  
3   CoreFoundation                      0x3324623d CFRunLoopRunSpecific + 356  
4   CoreFoundation                      0x332460c9 CFRunLoopRunInMode + 104  
5   GraphicsServices                    0x36e0133b GSEventRunModal + 74  
6   UIKit                               0x351622b9 UIApplicationMain + 1120  
7   CurrentTarget                       0x0000d6b3 main (main.m:15)  


Thread 1:  
0   libsystem_kernel.dylib              0x3b67d5d0 kevent64 + 24  
1   libdispatch.dylib                   0x3b5b4378 _dispatch_mgr_thread + 36  


Thread 2 Crashed:  
0   libobjc.A.dylib                     0x3b1945ca objc_msgSend + 9  
1   WebCore                             0x393d86c9   WebCore::LayerFlushScheduler::runLoopObserverCallback(__CFRunLoopObserver*, unsigned long, void*) + 25  
2   CoreFoundation                      0x332d4941   __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 21  
3   CoreFoundation                      0x332d2c39 __CFRunLoopDoObservers + 277  
4   CoreFoundation                      0x33246263 CFRunLoopRunSpecific + 394  
5   CoreFoundation                      0x332460c9 CFRunLoopRunInMode + 104  
6   WebCore                             0x3922a395 RunWebThread(void*) + 445  
7   libsystem_c.dylib                   0x3b5e60e1 _pthread_start + 309  


Thread 3:  
0   libsystem_kernel.dylib              0x3b67ce30 mach_msg_trap + 20  
1   CoreFoundation                      0x332d42bb __CFRunLoopServiceMachPort + 131  
2   CoreFoundation                      0x332d3031 __CFRunLoopRun + 905  
3   CoreFoundation                      0x3324623d CFRunLoopRunSpecific + 356  
4   CoreFoundation                      0x332460c9 CFRunLoopRunInMode + 104  
5   Foundation                          0x33b6a5c3 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 255  
6   Foundation                          0x33c0dc45 -[NSRunLoop(NSRunLoop) run] + 81
7   CurrentTarget                       0x0002db85 +[AFURLConnectionOperation networkRequestThreadEntryPoint:] (AFURLConnectionOperation.m:162)  
8   Foundation                          0x33c17231 __NSThread__main__ + 973  
9   libsystem_c.dylib                   0x3b5e60e1 _pthread_start + 309  


Thread 4:  
0   libsystem_kernel.dylib              0x3b67ce30 mach_msg_trap + 20  
1   CoreFoundation                      0x332d42bb __CFRunLoopServiceMachPort + 131  
2   CoreFoundation                      0x332d3031 __CFRunLoopRun + 905  
3   CoreFoundation                      0x3324623d CFRunLoopRunSpecific + 356  
4   CoreFoundation                      0x332460c9 CFRunLoopRunInMode + 104  
5   Foundation                          0x33b9388d +[NSURLConnection(Loader) _resourceLoadLoop:] + 309  
6   Foundation                          0x33c17231 __NSThread__main__ + 973  
7   libsystem_c.dylib                   0x3b5e60e1 _pthread_start + 309  



Thread 2 crashed with ARM Thread State:  
    r0: 0x00000004     r1: 0x39c10f51     r2: 0x000000cc     r3: 0x0ab29439   
    r4: 0x0940c600     r5: 0x1ed70618     r6: 0x1ed70610     r7: 0x0073edf8   
    r8: 0x00000003     r9: 0x00000000    r10: 0x0073ee20    r11: 0x0000008a    
    ip: 0x3cf14568     sp: 0x0073edec     lr: 0x39b7902b     pc: 0x3b1945ca   
  cpsr: 0x20000030