title: Application crash due to dereference garbage pointer
body: <p>I am seeing few random crashes in my iPod application with following message common in all the crash reports (though they have different thread traces). The crash is not reproducible - it occurs pretty randomly.</p>
  
  <p><strong>Attempted to dereference garbage pointer</strong></p>
  
  <p>I am also attaching a sample crash report. Please suggest as how to debug such an issue.</p>
  
  <p><strong>Crash Report:</strong></p>
  
  <p>CrashReporter Key:   6e6f41fdb678cf746d1c4561b2d7bc2b3f6772ad
      Hardware Model:      iPod4,1
      Process:         TestApplication [3154]
      Path:            /var/mobile/Applications/E5ED253B-A27A-4014-885A-030D19C7CB2C/TestApplication.app/TestApplication
      Identifier:      com.domain.retail.TestApplication
      Version:         1.0.0
      Code Type:       ARM
      Parent Process:  launchd [1]</p>
  
  <pre><code>Date/Time:       2013-04-02 10:37:29.000 +0530
  OS Version:      iPhone OS 6.1.3 (10B329)
  Report Version:  104
  
  Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
  Exception Codes: KERN_INVALID_ADDRESS at 0x000000cc
  Crashed Thread:  10
  
  Thread 0 name:  Dispatch queue: com.domain.main-thread
  Thread 0:
  0   libsystem_kernel.dylib          0x3a7bceb4 mach_msg_trap + 20
  1   CoreFoundation                  0x32626040 0x3258f000 + 618560
  2   CoreFoundation                  0x32624d58 0x3258f000 + 613720
  3   CoreFoundation                  0x32597eb8 CFRunLoopRunSpecific + 352
  4   CoreFoundation                  0x32597d48 CFRunLoopRunInMode + 104
  5   GraphicsServices                0x3614a2e8 GSEventRunModal + 72
  6   UIKit                           0x344ad300 UIApplicationMain + 1120
  7   TestApplication                          0x000a54d0 main + 44
  
  Thread 1 name:  Dispatch queue: com.domain.libdispatch-manager
  Thread 1:
  0   libsystem_kernel.dylib          0x3a7bd648 kevent64 + 24
  1   libdispatch.dylib               0x3a6e8df8 0x3a6e5000 + 15864
  
  Thread 2 name:  WebThread
  Thread 2:
  0   libsystem_kernel.dylib          0x3a7bceb4 mach_msg_trap + 20
  1   CoreFoundation                  0x32626040 0x3258f000 + 618560
  2   CoreFoundation                  0x32624da0 0x3258f000 + 613792
  3   CoreFoundation                  0x32597eb8 CFRunLoopRunSpecific + 352
  4   CoreFoundation                  0x32597d48 CFRunLoopRunInMode + 104
  5   WebCore                         0x38585500 0x3857b000 + 42240
  6   libsystem_c.dylib               0x3a726310 0x3a715000 + 70416
  
  Thread 3:
  0   libsystem_kernel.dylib          0x3a7cd6a4 __semwait_signal + 24
  1   Foundation                      0x32f0ac60 0x32eb7000 + 343136
  2   TestApplication                          0x0031c9c0 -[KSCrashDeadlockMonitor runMonitor] + 244
  3   Foundation                      0x32f67e80 0x32eb7000 + 724608
  4   libsystem_c.dylib               0x3a726310 0x3a715000 + 70416
  
  Thread 4 name:  KSCrash Exception Handler (Secondary)
  Thread 4:
  0   libsystem_kernel.dylib          0x3a7bceb4 mach_msg_trap + 20
  1   TestApplication                          0x00318b50 ksmachexc_i_handleExceptions + 124
  2   libsystem_c.dylib               0x3a726310 0x3a715000 + 70416
  
  Thread 5 name:  KSCrash Exception Handler (Primary)
  Thread 5:
  
  Thread 6 name:  com.domain.NSURLConnectionLoader
  Thread 6:
  0   libsystem_kernel.dylib          0x3a7bceb4 mach_msg_trap + 20
  1   CoreFoundation                  0x32626040 0x3258f000 + 618560
  2   CoreFoundation                  0x32624da0 0x3258f000 + 613792
  3   CoreFoundation                  0x32597eb8 CFRunLoopRunSpecific + 352
  4   CoreFoundation                  0x32597d48 CFRunLoopRunInMode + 104
  5   Foundation                      0x32ee43d0 0x32eb7000 + 185296
  6   Foundation                      0x32f67e80 0x32eb7000 + 724608
  7   libsystem_c.dylib               0x3a726310 0x3a715000 + 70416
  
  Thread 7 name:  com.domain.CFSocket.private
  Thread 7:
  0   libsystem_kernel.dylib          0x3a7cd594 select$DARWIN_EXTSN + 20
  1   libsystem_c.dylib               0x3a726310 0x3a715000 + 70416
  
  Thread 8 name:  JavaScriptCore::BlockFree
  Thread 8:
  0   libsystem_kernel.dylib          0x3a7cd08c __psynch_cvwait + 24
  1   libsystem_c.dylib               0x3a71eaa0 pthread_cond_timedwait + 40
  2   JavaScriptCore                  0x36540c70 _ZN3WTF15ThreadCondition9timedWaitERNS_5MutexEd + 104
  3   JavaScriptCore                  0x36652550 0x364e5000 + 1496400
  4   JavaScriptCore                  0x36664fa8 0x364e5000 + 1572776
  5   libsystem_c.dylib               0x3a726310 0x3a715000 + 70416
  
  Thread 9:
  0   libsystem_kernel.dylib          0x3a7cdd98 __workq_kernreturn + 8
  1   libsystem_c.dylib               0x3a71ba10 0x3a715000 + 27152
  
  Thread 10 name:  Dispatch queue: com.domain.root.high-priority
  Thread 10 Crashed:
  0   libicucore.A.dylib              0x39e5e570 ucol_getVersion + 0
  1   TextInput                       0x37d741b0 _ZN2KB8WordTrie4loadERKNS_6StringE + 280
  2   TextInput                       0x37d6d698 0x37d35000 + 231064
  3   TextInput                       0x380de2f8 0x37d35000 + 3838712
  4   TextInput                       0x380de298 0x37d35000 + 3838616
  5   TextInput                       0x37d65170 _ZN14TIInputManager17load_dictionariesERKN2KB6StringES3_b + 20
  6   TextInput                       0x37d761c8 0x37d35000 + 266696
  7   TextInput                       0x37d75e08 0x37d35000 + 265736
  8   UIKit                           0x3454ffd0 0x34456000 + 1023952
  9   UIKit                           0x3454f018 0x34456000 + 1019928
  10  UIKit                           0x3454ec28 0x34456000 + 1018920
  11  UIKit                           0x3454d500 0x34456000 + 1012992
  12  UIKit                           0x3454d1f0 0x34456000 + 1012208
  13  UIKit                           0x345afa48 0x34456000 + 1415752
  14  UIKit                           0x345ac918 0x34456000 + 1403160
  15  UIKit                           0x345ac618 0x34456000 + 1402392
  16  UIKit                           0x345ab018 0x34456000 + 1396760
  17  UIKit                           0x345aae40 0x34456000 + 1396288
  18  UIKit                           0x345aa780 0x34456000 + 1394560
  19  TestApplication                          0x00155e90 -[TestApplicationRequestInfoController showScanAlertForErrorType:Barcode:] + 2380
  20  TestApplication                          0x00151c48 -[TestApplicationRequestInfoController showAlertForErrorType:Barcode:] + 72
  21  TestApplication                          0x001fe090 -[TestApplicationBOPISOrdersScanningController processFirstNonSerialNumberScan:] + 3788
  22  TestApplication                          0x0020dd38 -[TestApplicationScanController processScanInfo] + 3512
  23  TestApplication                          0x0020cf38 __39-[TestApplicationScanController startScanThread]_block_invoke + 44
  24  libdispatch.dylib               0x3a6e7118 0x3a6e5000 + 8472
  25  libdispatch.dylib               0x3a6f5258 0x3a6e5000 + 66136
  26  libdispatch.dylib               0x3a6f53b8 0x3a6e5000 + 66488
  27  libsystem_c.dylib               0x3a71ba10 0x3a715000 + 27152
  
  Thread 11:
  0   libsystem_kernel.dylib          0x3a7bceb4 mach_msg_trap + 20
  1   CoreFoundation                  0x32626040 0x3258f000 + 618560
  2   CoreFoundation                  0x32624da0 0x3258f000 + 613792
  3   CoreFoundation                  0x32597eb8 CFRunLoopRunSpecific + 352
  4   CoreFoundation                  0x32597d48 CFRunLoopRunInMode + 104
  5   Foundation                      0x32ebaf90 0x32eb7000 + 16272
  6   Foundation                      0x32ec3d50 0x32eb7000 + 52560
  7   TestApplication                          0x002cc288 -[CommStream runLoopThread:] + 704
  8   Foundation                      0x32f67e80 0x32eb7000 + 724608
  9   libsystem_c.dylib               0x3a726310 0x3a715000 + 70416
  
  Thread 12:
  0   libsystem_kernel.dylib          0x3a7cd594 select$DARWIN_EXTSN + 20
  1   Foundation                      0x32f67e80 0x32eb7000 + 724608
  2   libsystem_c.dylib               0x3a726310 0x3a715000 + 70416
  
  Thread 13:
  0   libsystem_kernel.dylib          0x3a7bceb4 mach_msg_trap + 20
  1   CoreFoundation                  0x32626040 0x3258f000 + 618560
  2   CoreFoundation                  0x32624da0 0x3258f000 + 613792
  3   CoreFoundation                  0x32597eb8 CFRunLoopRunSpecific + 352
  4   CoreFoundation                  0x32597d48 CFRunLoopRunInMode + 104
  5   Foundation                      0x32ebaf90 0x32eb7000 + 16272
  6   Foundation                      0x32ec3d50 0x32eb7000 + 52560
  7   TestApplication                          0x002cc288 -[CommStream runLoopThread:] + 704
  8   Foundation                      0x32f67e80 0x32eb7000 + 724608
  9   libsystem_c.dylib               0x3a726310 0x3a715000 + 70416
  
  Thread 14:
  0   libsystem_kernel.dylib          0x3a7cd594 select$DARWIN_EXTSN + 20
  1   Foundation                      0x32f67e80 0x32eb7000 + 724608
  2   libsystem_c.dylib               0x3a726310 0x3a715000 + 70416
  
  Thread 15:
  0   libsystem_kernel.dylib          0x3a7cdd98 __workq_kernreturn + 8
  1   libsystem_c.dylib               0x3a71ba10 0x3a715000 + 27152
  
  Thread 10 crashed with ARM Thread State:
      r0: 0x00000000     r1: 0x05fe1320     r2: 0x00000001     r3: 0x00000001 
      r4: 0x03000000     r5: 0x07000000     r6: 0x05a1c000     r7: 0x05fe1394 
      r8: 0x05fe14d8     r9: 0x00000000    r10: 0x37d5f865    r11: 0x05fe14c8 
      ip: 0x3be8e2bc     sp: 0x05fe1300     lr: 0x37d74427     pc: 0x39e5e570 
    cpsr: 0x20000030 
  
  CrashDoctor Diagnosis: Attempted to dereference garbage pointer 0xcc.
  Originated at or in a subcall of -[TestApplicationRequestInfoController showScanAlertForErrorType:Barcode:]
  </code></pre>