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Deadlock: Out-of-Sequence Step Value

Time

Thread #
(my_step)

current_step

Action

0

3

0

Thread 3 executes first time: predicate is FALSE -> wait()

1

2

0

Thread 2 executes first time: predicate is FALSE -> wait()

2

4

0

Thread 4 executes first time: predicate is FALSE -> wait()

3

0

0

Thread 0 executes first time: predicate is TRUE -> current_step++; cnd_signal()

4

1

1

Thread 1 executes first time: predicate is TRUE -> current_step++; cnd_signal()

5

3

2

Thread 3 wakes up (scheduler choice): predicate is FALSE -> wait()

6

Thread exhaustion! No more threads to run, and a conditional variable signal is needed to wake up the others

This noncompliant code example violates the liveness property.

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Failing to preserve the thread safety and liveness of a program when using condition variables can lead to indefinite blocking and denial of service (DoS).

Rule

Severity

Likelihood

Remediation Cost

Priority

Level

CON38-C

Low

Unlikely

Medium

P2

L3

Automated Detection

Tool

Version

Checker

Description

CodeSonar
Include Page
CodeSonar_V
CodeSonar_V

CONCURRENCY.BADFUNC.CNDSIGNAL

Use of Condition Variable Signal

Cppcheck Premium

Include Page
Cppcheck Premium_V
Cppcheck Premium_V

premium-cert-con38-cFully implemented
Helix QAC

Include Page
Helix QAC_V
Helix QAC_V

C1778, C1779


Klocwork
Include Page
Klocwork_V
Klocwork_V

CERT.CONC.UNSAFE_COND_VAR_C


Parasoft C/C++test

Include Page
Parasoft_V
Parasoft_V

CERT_C-CON38-a

Use the 'cnd_signal()' function with a unique condition variable

Polyspace Bug Finder

Include Page
Polyspace Bug Finder_V
Polyspace Bug Finder_V

CERT C: Rule CON38-CChecks for multiple threads waiting on same condition variable (rule fully covered)

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

Related Guidelines

Key here (explains table format and definitions)

Taxonomy

Taxonomy item

Relationship

CERT Oracle Secure Coding Standard for JavaTHI02-J. Notify all waiting threads rather than a single threadPrior to 2018-01-12: CERT: Unspecified Relationship

Bibliography

[IEEE Std 1003.1:2013]XSH, System Interfaces, pthread_cond_broadcast
XSH, System Interfaces, pthread_cond_signal
[Lea 2000]
 

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