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The DEFAULT mutex type of pthreads is also generally mapped to PTHREAD_MUTEX_NORMAL, but is known to vary from platform to platform \[[SOL 10|http://docs.sun.com/app/docs/doc/816-5137/sync-28983?a=view] \]. Usage of NORMAL locks should thus be avoided and ERRORCHECK or RECURSIVE locks should be explicitly defined when using mutex locks. |
Noncompliant Code Example
The non compliant code example shows a simple mutex being created using PTHREAD_MUTEX_NORMAL. It should be noted that no return code is expected by the caller when NORMAL mutexes are used.
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pthread_mutexattr_t attr;
pthread_mutex_t mutex;
size_t const shared_var = 0;
int main(){
int rc =0;
rc = pthread_mutexattr_settype(&mutex, PTHREAD_MUTEX_NORMAL);
if(rc != 0){
/* Handle Error */
}
rc = pthread_mutex_init(&mutex, &attr);
if(rc != 0){
/* Handle Error */
}
pthread_mutex_lock(&mutex);
/* Critical Region*/
pthread_mutex_unlock(&mutex);
return 0;
}
|
Compliant Solution
The compliant solution shows a pthread mutex lock being created with type PTHREAD_MUTEX_ERRORCHECK where return codes will be available during locking and unlocking.
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|---|---|---|
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pthread_mutexattr_t attr;
pthread_mutex_t mutex;
size_t const shared_var = 0;
int main(){
int rc =0;
rc = pthread_mutexattr_settype(&mutex, PTHREAD_MUTEX_ERRORCHECK);
if(rc != 0){
/* Handle Error */
}
rc = pthread_mutex_init(&mutex, &attr);
if(rc != 0){
/* Handle Error */
}
rc = pthread_mutex_lock(&mutex);
if(rc != 0){
/* Handle Error */
}
/* Critical Region*/
rc = pthread_mutex_unlock(&mutex);
if(rc != 0){
/* Handle Error */
}
return 0;
}
|
Risk Assessment
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
POSXX POS04-C | high low | likely | medium | P12 P6 | L1 L2 |
References
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\[[Open Group 4|https://www.securecoding.cert.org/confluence/display/seccode/AA.+C+References#AA.CReferences-OpenGroup04] \] \[[SOL 10|http://docs.sun.com/app/docs/doc/816-5137/sync-28983?a=view] \] |