windbg 经典死锁调试

时间：2022-03-10 17:23

代码

这是一个经典死锁，开启两个线程，一个以123的次序拿锁，一个以321次序拿锁，互相等待着对方的锁而均不释放自己手中的锁。(此处锁也指CriticalSection)

开启WINDBG 附加死锁进程，查看 0:003> ~* kv 0 Id: 2b8.2f0 Suspend: 1 Teb: 7ffdf000 Unfrozen ChildEBP RetAddr Args to Child WARNING: Stack unwind information not available. Following frames may be wrong. 0012ff6c 0042e346 00000001 003c30b8 003c3168 Deadlock_Debug+0x2d85c 0012ffb8 0042e21f 0012fff0 7c816d4f 0007da50 Deadlock_Debug+0x2e346 0012ffc0 7c816d4f 0007da50 7c92e1fe 7ffd9000 Deadlock_Debug+0x2e21f 0012fff0 00000000 0042b523 00000000 78746341 kernel32!BaseProcessStart+0x23 (FPO: [Non-Fpo]) 1 Id: 2b8.1e0 Suspend: 1 Teb: 7ffde000 Unfrozen ChildEBP RetAddr Args to Child 0059fe00 7c92e9c0 7c93901b 00000030 00000000 ntdll!KiFastSystemCallRet (FPO: [0,0,0]) 0059fe04 7c93901b 00000030 00000000 00000000 ntdll!ZwWaitForSingleObject+0xc (FPO: [3,0,0]) 0059fe8c 7c92104b 004944f0 0042d5e0 004944f0 ntdll!RtlpWaitForCriticalSection+0x132 (FPO: [1,26,4]) 0059fe94 0042d5e0 004944f0 57565554 5b5a5958 ntdll!RtlEnterCriticalSection+0x46 (FPO: [1,0,0]) WARNING: Stack unwind information not available. Following frames may be wrong. 0059ff6c 0042e123 00000000 2d7b25f9 57565554 Deadlock_Debug+0x2d5e0 0059ffa8 0042e094 00000000 0059ffec 7c80b50b Deadlock_Debug+0x2e123 0059ffb4 7c80b50b 003c2c20 57565554 5b5a5958 Deadlock_Debug+0x2e094 0059ffec 00000000 0042dff0 003c2c20 00000000 kernel32!BaseThreadStart+0x37 (FPO: [Non-Fpo]) 2 Id: 2b8.1e4 Suspend: 1 Teb: 7ffdd000 Unfrozen ChildEBP RetAddr Args to Child 0069fe00 7c92e9c0 7c93901b 00000034 00000000 ntdll!KiFastSystemCallRet (FPO: [0,0,0]) 0069fe04 7c93901b 00000034 00000000 00000000 ntdll!ZwWaitForSingleObject+0xc (FPO: [3,0,0]) 0069fe8c 7c92104b 004944c0 0042d714 004944c0 ntdll!RtlpWaitForCriticalSection+0x132 (FPO: [1,26,4]) 0069fe94 0042d714 004944c0 57565554 5b5a5958 ntdll!RtlEnterCriticalSection+0x46 (FPO: [1,0,0]) WARNING: Stack unwind information not available. Following frames may be wrong. 0069ff6c 0042e123 00000000 2d4b25f9 57565554 Deadlock_Debug+0x2d714 0069ffa8 0042e094 00000000 0069ffec 7c80b50b Deadlock_Debug+0x2e123 0069ffb4 7c80b50b 003c2e60 57565554 5b5a5958 Deadlock_Debug+0x2e094 0069ffec 00000000 0042dff0 003c2e60 00000000 kernel32!BaseThreadStart+0x37 (FPO: [Non-Fpo]) # 3 Id: 2b8.948 Suspend: 1 Teb: 7ffdc000 Unfrozen ChildEBP RetAddr Args to Child 0038ffc8 7c9707a8 00000005 00000004 00000001 ntdll!DbgBreakPoint (FPO: [0,0,0]) 0038fff4 00000000 00000000 00000000 00000000 ntdll!DbgUiRemoteBreakin+0x2d (FPO: [Non-Fpo]) //////////////////////////////////////////////////// 在切换到线程2 1进行观察可以看到均是在等待CriticalSection 0:003> ~2 kv ChildEBP RetAddr Args to Child 0069fe00 7c92e9c0 7c93901b 00000034 00000000 ntdll!KiFastSystemCallRet (FPO: [0,0,0]) 0069fe04 7c93901b 00000034 00000000 00000000 ntdll!ZwWaitForSingleObject+0xc (FPO: [3,0,0]) 0069fe8c 7c92104b 004944c0 0042d714 004944c0 ntdll!RtlpWaitForCriticalSection+0x132 (FPO: [1,26,4]) 0069fe94 0042d714 004944c0 57565554 5b5a5958 ntdll!RtlEnterCriticalSection+0x46 (FPO: [1,0,0] 0:003> ~1 kv ChildEBP RetAddr Args to Child 0059fe00 7c92e9c0 7c93901b 00000030 00000000 ntdll!KiFastSystemCallRet (FPO: [0,0,0]) 0059fe04 7c93901b 00000030 00000000 00000000 ntdll!ZwWaitForSingleObject+0xc (FPO: [3,0,0]) 0059fe8c 7c92104b 004944f0 0042d5e0 004944f0 ntdll!RtlpWaitForCriticalSection+0x132 (FPO: [1,26,4]) 0059fe94 0042d5e0 004944f0 57565554 5b5a5958 ntdll!RtlEnterCriticalSection+0x46 (FPO: [1,0,0]) ////////////////////////////////////////////// 使用!LOCKS指令查看当前的锁 0:003> !locks CritSec Deadlock_Debug+944f0 at 004944f0 LockCount 1 RecursionCount 1 OwningThread 1e4 EntryCount 1 ContentionCount 1 *** Locked CritSec Deadlock_Debug+944d8 at 004944d8 LockCount 0 RecursionCount 1 OwningThread 1e4 EntryCount 0 ContentionCount 0 *** Locked CritSec Deadlock_Debug+944c0 at 004944c0 LockCount 1 RecursionCount 1 OwningThread 1e0 EntryCount 1 ContentionCount 1 *** Locked

比对线程等待的锁及个锁的拥有者和锁定情况变可以判断
线程编号1e4 也就是线程2 等待004944c0 的锁（根据堆栈的RtlEnterCriticalSection函数部分查看）
0069fe94 0042d714 004944c0 57565554 5b5a5958 ntdll!RtlEnterCriticalSection+0x46 (FPO: [1,0,0])

而004844c0的锁由线程编号1e0 就是线程1持有
而线程编号1e0 就是线程1 等待004944f0 的锁该所有线程编号1e4持有
0059fe94 0042d5e0 004944f0 57565554 5b5a5958 ntdll!RtlEnterCriticalSection+0x46 (FPO: [1,0,0])

死锁！！！
找到原因就好修正了。

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