mutex as argument

[kheradmand]

Strator has problems when it comes to mutexes as function argument. It will assume each function argument is a different mutex irrelevant of the path. this will cause problems in some situations. Both causes false negatives and false positives.
Solution is to write something like getDefOperand but flow-sensitive, and only for values that depend on only one other value (bitcasts, argument passings, ...)

[kheradmand]

for example in this situation:

void* f1(void* arg){
    pthread_mutex_t* m = (pthread_mutex_t*)(arg);
    pthread_mutex_lock(m);
    global++;
    pthread_mutex_unlock(m);
    printf("f1\n");
    return 0;
}

void* f2(void* arg){
    pthread_mutex_t* m = (pthread_mutex_t*)(arg);
    pthread_mutex_lock(m);
    global++;
    pthread_mutex_unlock(m);
    printf("f2\n");
    return 0;
}



int main(){
    pthread_t t1,t2;

    pthread_mutex_init(&m1, NULL);
    pthread_mutex_init(&m2, NULL);

    pthread_create(&t1, NULL, f1, (void*)(&m1));
    pthread_create(&t2, NULL, f2, (void*)(&m1));

    pthread_join(t1, NULL);
    pthread_join(t2, NULL);

    printf("%d\n",global);


    return 0;
}

Strator reports races for accesses to global in f1 and f2. but Relay correctly does not.

[kheradmand]

Or in this one:

pthread_mutex_t m1,m2;
int global;

void* f1(void* arg){
    pthread_mutex_t* m = (pthread_mutex_t*)(arg);
    pthread_mutex_lock(m);
    global++;
    pthread_mutex_unlock(m);
    printf("f1\n");
    return 0;
}




int main(){
    pthread_t t1,t2;

    pthread_mutex_init(&m1, NULL);
    pthread_mutex_init(&m2, NULL);

    pthread_create(&t1, NULL, f1, (void*)(&m1));
    pthread_create(&t2, NULL, f1, (void*)(&m2));

    pthread_join(t1, NULL);
    pthread_join(t2, NULL);

    printf("%d\n",global);


    return 0;
}

Both Strator and Relay give false negatives