界: Time and State

分散式運算與時間和狀態相關。也就是說，為了使多個元件進行通訊，必須共用狀態，並且這一切都需要時間。

大多數的程式設計師將他們的工作擬人化。他們想採用一種控制執行緒來執行整個程式，就像他們必須自己完成這項工作一樣。但是，現代的電腦可以非常快速地切換工作，並且在多核心多 CPU 或分散式系統中，兩個事件可能恰好同時發生。瑕疵急於填補程式設計師在程式執行模型與實際情況之間的差距。這些瑕疵與執行緒、處理序、時間和資訊之間的意外互動有關。這些互動透過共用狀態發生：信號、變數、檔案系統，以及基本上任何可以儲存資訊的項目。

Code Correctness: Erroneous Synchronization

Abstract
如果執行緒沒能在向其他執行緒發訊號後解除 mutex 鎖定，其他執行緒仍會維持鎖定，並在 mutex 繼續等待。
Explanation
在執行緒對其他在 mutex 等待的執行緒發出訊號後，它必須在另一個 pthread_mutex_unlock() 函數能開始執行之前，先呼叫此函數來解除 mutex 鎖定。如果發出訊號的執行緒沒能解除 mutex 鎖定，就不會回傳在第二個執行緒呼叫的 pthread_cond_wait()，而且也不會執行該執行緒。

範例 1：以下程式碼藉由呼叫 pthread_cond_signal()，對一個在 mutex 上等待的執行緒發出訊號，但卻無法解除另一個執行緒在等待的 mutex 鎖定。


   ...
   pthread_mutex_lock(&count_mutex);

   // Signal waiting thread
   pthread_cond_signal(&count_threshold_cv);
   ...
References
[1] Standards Mapping - CIS Azure Kubernetes Service Benchmark 1
[2] Standards Mapping - CIS Amazon Elastic Kubernetes Service Benchmark 2
[3] Standards Mapping - CIS Amazon Web Services Foundations Benchmark 1
[4] Standards Mapping - CIS Google Kubernetes Engine Benchmark normal
[5] Standards Mapping - Common Weakness Enumeration CWE ID 373
[6] Standards Mapping - DISA Control Correlation Identifier Version 2 CCI-001094
[7] Standards Mapping - Motor Industry Software Reliability Association (MISRA) C Guidelines 2012 Rule 1.3
[8] Standards Mapping - NIST Special Publication 800-53 Revision 4 SC-5 Denial of Service Protection (P1)
[9] Standards Mapping - NIST Special Publication 800-53 Revision 5 SC-5 Denial of Service Protection
[10] Standards Mapping - OWASP Top 10 2004 A9 Application Denial of Service
[11] Standards Mapping - Payment Card Industry Data Security Standard Version 1.1 Requirement 6.5.9
[12] Standards Mapping - Security Technical Implementation Guide Version 3.1 APP6080 CAT II
[13] Standards Mapping - Security Technical Implementation Guide Version 3.4 APP6080 CAT II
[14] Standards Mapping - Security Technical Implementation Guide Version 3.5 APP6080 CAT II
[15] Standards Mapping - Security Technical Implementation Guide Version 3.6 APP6080 CAT II
[16] Standards Mapping - Security Technical Implementation Guide Version 3.7 APP6080 CAT II
[17] Standards Mapping - Security Technical Implementation Guide Version 3.9 APP6080 CAT II
[18] Standards Mapping - Security Technical Implementation Guide Version 3.10 APP6080 CAT II
[19] Standards Mapping - Security Technical Implementation Guide Version 4.1 APSC-DV-002400 CAT II
[20] Standards Mapping - Security Technical Implementation Guide Version 4.2 APSC-DV-002400 CAT II
[21] Standards Mapping - Security Technical Implementation Guide Version 4.3 APSC-DV-002400 CAT II
[22] Standards Mapping - Security Technical Implementation Guide Version 4.4 APSC-DV-002400 CAT II
[23] Standards Mapping - Security Technical Implementation Guide Version 4.5 APSC-DV-002400 CAT II
[24] Standards Mapping - Security Technical Implementation Guide Version 4.6 APSC-DV-002400 CAT II
[25] Standards Mapping - Security Technical Implementation Guide Version 4.7 APSC-DV-002400 CAT II
[26] Standards Mapping - Security Technical Implementation Guide Version 4.8 APSC-DV-002400 CAT II
[27] Standards Mapping - Security Technical Implementation Guide Version 4.9 APSC-DV-002400 CAT II
[28] Standards Mapping - Security Technical Implementation Guide Version 4.10 APSC-DV-002400 CAT II
[29] Standards Mapping - Security Technical Implementation Guide Version 4.11 APSC-DV-002400 CAT II
[30] Standards Mapping - Security Technical Implementation Guide Version 5.1 APSC-DV-002400 CAT II
[31] Standards Mapping - Security Technical Implementation Guide Version 5.2 APSC-DV-002400 CAT II
[32] Standards Mapping - Security Technical Implementation Guide Version 5.3 APSC-DV-002400 CAT II, APSC-DV-002950 CAT II
[33] Standards Mapping - Web Application Security Consortium Version 2.00 Denial of Service (WASC-10)
[34] Standards Mapping - Web Application Security Consortium 24 + 2 Denial of Service
desc.structural.cpp.code_correctness_erroneous_synchronization