使用 Address Sanitizer 发现了一个 bug,日志该怎么看，如何去找到问题出在哪里？

[changhogliang]

xcode 的日志如下：

==581==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x000117e1ea68 at pc 0x000100d2500c bp 0x00016e045830 sp 0x00016e045828 READ of size 8 at 0x000117e1ea68 thread T3

    #0 0x100d2500b in __64+[NetworkObserver injectIntoAllNSURLConnectionDelegateClasses]_block_invoke (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/iosapp+0x100c5d00b)
    #1 0x1017a521b in _dispatch_client_callout (/usr/lib/system/introspection/libdispatch.dylib+0x121b)
    #2 0x1017a604b in dispatch_once_f (/usr/lib/system/introspection/libdispatch.dylib+0x204b)
    #3 0x100d24913 in +[NetworkObserver injectIntoAllNSURLConnectionDelegateClasses] (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/iosapp+0x100c5c913)
    #4 0x100d239fb in +[NetworkObserver setEnabled:] (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/iosapp+0x100c5b9fb)
    #5 0x100d70a73 in __26+[AP startWithAppID:]_block_invoke (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/iosapp+0x100ca8a73)
    #6 0x100d8489f in __47-[ConnectionQueue connectHostWithCompletion:]_block_invoke_2 (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/iosapp+0x100cbc89f)
    #7 0x18e752617 in <redacted> (/System/Library/Frameworks/CFNetwork.framework/CFNetwork+0x3617)
    #8 0x18e769317 in <redacted> (/System/Library/Frameworks/CFNetwork.framework/CFNetwork+0x1a317)
    #9 0x18ec157e3 in <redacted> (/System/Library/Frameworks/Foundation.framework/Foundation+0xe57e3)
    #10 0x18eb5a357 in <redacted> (/System/Library/Frameworks/Foundation.framework/Foundation+0x2a357)
    #11 0x18eb4a953 in <redacted> (/System/Library/Frameworks/Foundation.framework/Foundation+0x1a953)
    #12 0x18ec17b8f in <redacted> (/System/Library/Frameworks/Foundation.framework/Foundation+0xe7b8f)
    #13 0x10191f097 in asan_dispatch_call_block_and_release (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/Frameworks/libclang_rt.asan_ios_dynamic.dylib+0x3b097)
    #14 0x1017a521b in _dispatch_client_callout (/usr/lib/system/introspection/libdispatch.dylib+0x121b)
    #15 0x1017b2b53 in _dispatch_queue_serial_drain (/usr/lib/system/introspection/libdispatch.dylib+0xeb53)
    #16 0x1017a8ce3 in _dispatch_queue_invoke (/usr/lib/system/introspection/libdispatch.dylib+0x4ce3)
    #17 0x1017b4e6b in _dispatch_root_queue_drain (/usr/lib/system/introspection/libdispatch.dylib+0x10e6b)
    #18 0x1017b4bb7 in _dispatch_worker_thread3 (/usr/lib/system/introspection/libdispatch.dylib+0x10bb7)
    #19 0x18d1e52c7 in _pthread_wqthread (/usr/lib/system/libsystem_pthread.dylib+0x12c7)
    #20 0x18d1e4db3 in start_wqthread (/usr/lib/system/libsystem_pthread.dylib+0xdb3)```
</br>
0x000117e1ea68 is located 0 bytes to the right of 123496-byte region [0x000117e00800,0x000117e1ea68)
allocated by thread T3 here:
``` #0 0x1019206f7 in wrap_malloc (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/Frameworks/libclang_rt.asan_ios_dynamic.dylib+0x3c6f7)
    #1 0x100d24f9f in __64+[NetworkObserver injectIntoAllNSURLConnectionDelegateClasses]_block_invoke (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/iosapp+0x100c5cf9f)
    #2 0x1017a521b in _dispatch_client_callout (/usr/lib/system/introspection/libdispatch.dylib+0x121b)
    #3 0x1017a604b in dispatch_once_f (/usr/lib/system/introspection/libdispatch.dylib+0x204b)
    #4 0x100d24913 in +[NetworkObserver injectIntoAllNSURLConnectionDelegateClasses] (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/iosapp+0x100c5c913)
    #5 0x100d239fb in +[NetworkObserver setEnabled:] (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/iosapp+0x100c5b9fb)
    #6 0x100d70a73 in __26+[AP startWithAppID:]_block_invoke (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/iosapp+0x100ca8a73)
    #7 0x100d8489f in __47-[ConnectionQueue connectHostWithCompletion:]_block_invoke_2 (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/iosapp+0x100cbc89f)
    #8 0x18e752617 in <redacted> (/System/Library/Frameworks/CFNetwork.framework/CFNetwork+0x3617)
    #9 0x18e769317 in <redacted> (/System/Library/Frameworks/CFNetwork.framework/CFNetwork+0x1a317)
    #10 0x18ec157e3 in <redacted> (/System/Library/Frameworks/Foundation.framework/Foundation+0xe57e3)
    #11 0x18eb5a357 in <redacted> (/System/Library/Frameworks/Foundation.framework/Foundation+0x2a357)
#12 0x18eb4a953 in <redacted> (/System/Library/Frameworks/Foundation.framework/Foundation+0x1a953)
    #13 0x18ec17b8f in <redacted> (/System/Library/Frameworks/Foundation.framework/Foundation+0xe7b8f)
    #14 0x10191f097 in asan_dispatch_call_block_and_release (/var/containers/Bundle/Application/98800CF8-BBF8-4B69-A29F-A988509D1600/iosapp.app/Frameworks/libclang_rt.asan_ios_dynamic.dylib+0x3b097)
    #15 0x1017a521b in _dispatch_client_callout (/usr/lib/system/introspection/libdispatch.dylib+0x121b)
    #16 0x1017b2b53 in _dispatch_queue_serial_drain (/usr/lib/system/introspection/libdispatch.dylib+0xeb53)
    #17 0x1017a8ce3 in _dispatch_queue_invoke (/usr/lib/system/introspection/libdispatch.dylib+0x4ce3)
    #18 0x1017b4e6b in _dispatch_root_queue_drain (/usr/lib/system/introspection/libdispatch.dylib+0x10e6b)
    #19 0x1017b4bb7 in _dispatch_worker_thread3 (/usr/lib/system/introspection/libdispatch.dylib+0x10bb7)
    #20 0x18d1e52c7 in _pthread_wqthread (/usr/lib/system/libsystem_pthread.dylib+0x12c7)
    #21 0x18d1e4db3 in start_wqthread (/usr/lib/system/libsystem_pthread.dylib+0xdb3)

Thread T3 created by T1 here: <empty stack="">
Thread T1 created by T0 here:

    #1 0x1028c53eb in GPUTools::Interpose::DYInitInterpose(DYGuestAppClient* (*)(), int) (/Developer/Library/PrivateFrameworks/GPUToolsCore.framework/GPUToolsCore+0x113eb)
    #2 0x10187595b  (<unknown module>)
    #3 0x101875b83  (<unknown module>)
    #4 0x101870f2b  (<unknown module>)
    #5 0x10186ff4f  (<unknown module>)
    #6 0x101870003  (<unknown module>)
    #7 0x101862463  (<unknown module>)
    #8 0x1018668f3  (<unknown module>)
    #9 0x101861043  (<unknown module>) ```

    SUMMARY: AddressSanitizer: heap-buffer-overflow ??:0 __64+[NetworkObserver injectIntoAllNSURLConnectionDelegateClasses]_block_invoke
Shadow bytes around the buggy address:<br><br>
0x0001431c3cf0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00<br>
0x0001431c3d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00<br>
0x0001431c3d10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00<br>
0x0001431c3d20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00<br>
 0x0001431c3d30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00<br>
=>0x0001431c3d40: 00 00 00 00 00 00 00 00 00 00 00 00 00[fa]fa fa<br>
0x0001431c3d50: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa<br>
0x0001431c3d60: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa<br>
0x0001431c3d70: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa<br>
0x0001431c3d80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa<br>
0x0001431c3d90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa<br>
Shadow byte legend (one shadow byte represents 8 application bytes):<br>
  Addressable:           00<br>
  Partially addressable: 01 02 03 04 05 06 07<br>
  Heap left redzone:       fa<br>
  Heap right redzone:      fb<br>
  Freed heap region:       fd<br>
  Stack left redzone:      f1<br>
  Stack mid redzone:       f2<br>
  Stack partial redzone:   f4<br>
  Stack after return:      f5<br>
  Stack use after scope:   f8<br>
  Global redzone:          f9<br>
  Global init order:       f6<br>
  Poisoned by user:        f7<br>
  Container overflow:      fc<br>
  Array cookie:            ac<br>
  Intra object redzone:    bb<br>
  ASan internal:           fe<br>
  Left alloca redzone:     ca<br>
  Right alloca redzone:    cb<br><br>
==581==ABORTING<br>
Warning: hit breakpoint while running function, skipping commands and conditions to prevent recursion.warning: could not load any Objective-C class information from the dyld shared cache. This will significantly reduce the quality of type information available.
AddressSanitizer report breakpoint hit. Use 'thread info -s' to get extended information about the report.

崩溃的线程：

* thread #5: tid = 0x14006, 0x0000000101929470 libclang_rt.asan_ios_dynamic.dylib`__asan::AsanDie(), queue = 'NSOperationQueue 0x114563b50 :: NSOperation 0x10b9be650 (QOS: DEFAULT)', stop reason = Heap buffer overflow detected
    frame #0: 0x0000000101929470 libclang_rt.asan_ios_dynamic.dylib`__asan::AsanDie()
    frame #1: 0x000000010192cf2c libclang_rt.asan_ios_dynamic.dylib`__sanitizer::Die() + 44
    frame #2: 0x0000000101928280 libclang_rt.asan_ios_dynamic.dylib`__asan::ScopedInErrorReport::~ScopedInErrorReport() + 336
    frame #3: 0x0000000101928018 libclang_rt.asan_ios_dynamic.dylib`__asan::ScopedInErrorReport::~ScopedInErrorReport() + 12
    frame #4: 0x0000000101927b94 libclang_rt.asan_ios_dynamic.dylib`__asan_report_error + 3216
    frame #5: 0x0000000101928534 libclang_rt.asan_ios_dynamic.dylib`__asan_report_load8 + 44
  * frame #6: 0x0000000100d2500c iosapp`__64+[NetworkObserver injectIntoAllNSURLConnectionDelegateClasses]_block_invoke(.block_descriptor=<unavailable>) + 1632 at NetworkObserver.m:190
    frame #7: 0x00000001017a521c libdispatch.dylib`_dispatch_client_callout + 16
    frame #8: 0x00000001017a604c libdispatch.dylib`dispatch_once_f + 116
    frame #9: 0x0000000100d24914 iosapp`+[NetworkObserver injectIntoAllNSURLConnectionDelegateClasses] [inlined] _dispatch_once(predicate=0x00000001011c2760, block=(iosapp`__64+[NetworkObserver injectIntoAllNSURLConnectionDelegateClasses]_block_invoke at NetworkObserver.m:162)) + 124 at once.h:68
    frame #10: 0x0000000100d24898 iosapp`+[NetworkObserver injectIntoAllNSURLConnectionDelegateClasses](self=NetworkObserver, _cmd="injectIntoAllNSURLConnectionDelegateClasses") + 832 at NetworkObserver.m:162
    frame #11: 0x0000000100d239fc iosapp`+[NetworkObserver setEnabled:](self=NetworkObserver, _cmd="setEnabled:", enabled=YES) + 240 at NetworkObserver.m:89
    frame #12: 0x0000000100d70a74 iosapp`__26+[AP startWithAppID:]_block_invoke(.block_descriptor=<unavailable>, success=YES) + 236 at AP.m:61
    frame #13: 0x0000000100d848a0 iosapp`__47-[ConnectionQueue connectHostWithCompletion:]_block_invoke_2(.block_descriptor=<unavailable>, data=<unavailable>, response=<unavailable>, error=<unavailable>) + 1096 at RAConnectionQueue.m:175
    frame #14: 0x000000018e752618 CFNetwork`__75-[__NSURLSessionLocal taskForClass:request:uploadFile:bodyData:completion:]_block_invoke + 32
    frame #15: 0x000000018e769318 CFNetwork`__49-[__NSCFLocalSessionTask _task_onqueue_didFinish]_block_invoke + 296
    frame #16: 0x000000018ec157e4 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 16
    frame #17: 0x000000018eb5a358 Foundation`-[NSBlockOperation main] + 96
    frame #18: 0x000000018eb4a954 Foundation`-[__NSOperationInternal _start:] + 620
    frame #19: 0x000000018ec17b90 Foundation`__NSOQSchedule_f + 228
    frame #20: 0x000000010191f098 libclang_rt.asan_ios_dynamic.dylib`asan_dispatch_call_block_and_release + 264
    frame #21: 0x00000001017a521c libdispatch.dylib`_dispatch_client_callout + 16
    frame #22: 0x00000001017b2b54 libdispatch.dylib`_dispatch_queue_serial_drain + 1136
    frame #23: 0x00000001017a8ce4 libdispatch.dylib`_dispatch_queue_invoke + 672
    frame #24: 0x00000001017b4e6c libdispatch.dylib`_dispatch_root_queue_drain + 584
    frame #25: 0x00000001017b4bb8 libdispatch.dylib`_dispatch_worker_thread3 + 140
    frame #26: 0x000000018d1e52c8 libsystem_pthread.dylib`_pthread_wqthread + 1288

xcode 停留的位置：

 Class *classes = NULL;
        int numClasses = objc_getClassList(NULL, 0);

        if (numClasses > 0) {
            classes = (__unsafe_unretained Class *)malloc(sizeof(Class) * numClasses);
            numClasses = objc_getClassList(classes, numClasses);
            for (NSInteger classIndex = 0; classIndex < numClasses; ++classIndex) {
                Class class = classes[classIndex];

                if (class == [NetworkObserver class] ||
                    class == [ConnectionQueue class] ||
                    class == [HTTPProtocol class]) {
                    continue;
                }

最后停留在 Class class = classes[classIndex];问题可能出在哪里？

[TJT]

这种是典型的数组越界吧， numClasses 重新赋值了，应该是这里出错了。

[changhogliang]

@TJT 看了下断点， classIndex 的值为 15437 ， numClasses 为 15441.显然没有越界。

[cute]

试试这样呢

unsigned int numClasses;
Class *classes = objc_copyClassList(&numClasses);
for (unsigned int i = 0; i < numClasses; i++) {
Class cls = classes[i];
NSLog(@"class name: %s", class_getName(cls));
}
free(classes);

[changhogliang]

@cute 谢谢，已经解决了， iOS 子线程的默认堆栈为 512k ，比较小，子线程做了很多操作，特别是这个比较大的数组，导致溢出，我在这里重新开了个线程，问题解决了。

[cute]

@changhogliang 学习了