[CRIU] [PATCH] zdtm: fix sigpending to check blocked signal masks

[Andrew Vagin]

On Wed, May 22, 2013 at 03:48:26PM +0400, Pavel Emelyanov wrote:
> On 05/22/2013 03:46 PM, Andrey Vagin wrote:
> > Here are a few bugs which hide each other.
>

* memcmp(&newset, &oldset, sizeof(newset) returns 0 is masks are equal.
* sigprocmask return sigset_t and it contains extra bits for the future,
so we need to initialize all this bits otherwise they will contain
random data.

> Plz, describe them.
> 
> > Signed-off-by: Andrey Vagin <avagin at openvz.org>
> > ---
> >  test/zdtm/live/static/sigpending.c | 18 ++++++++++++++----
> >  1 file changed, 14 insertions(+), 4 deletions(-)
> > 
> > diff --git a/test/zdtm/live/static/sigpending.c b/test/zdtm/live/static/sigpending.c
> > index ce47f60..05471f9 100644
> > --- a/test/zdtm/live/static/sigpending.c
> > +++ b/test/zdtm/live/static/sigpending.c
> > @@ -91,6 +91,9 @@ static void *thread_fn(void *args)
> >  	sigset_t blockmask, oldset, newset;
> >  	struct sigaction act;
> >  
> > +	memset(&oldset, 0, sizeof(oldset));
> > +	memset(&newset, 0, sizeof(oldset));
> > +

 sigprocmask return sigset_t and it contains extra bits for the future,
so we need to initialize all this bits otherwise they will contain
random data.

> >  	sigfillset(&blockmask);
> >  	sigdelset(&blockmask, SIGTERM);
> >  
> > @@ -99,7 +102,7 @@ static void *thread_fn(void *args)
> >  		return NULL;
> >  	}
> >  
> > -	if (sigprocmask(SIG_BLOCK, NULL, &oldset) == -1) {
> > +	if (sigprocmask(SIG_SETMASK, NULL, &oldset) == -1) {
> >  		err("sigprocmask");
> >  		return NULL;
> >  	}
> > @@ -125,7 +128,9 @@ static void *thread_fn(void *args)
> >  		return NULL;
> >  	}
> >  
> > -	if (!memcmp(&newset, &oldset, sizeof(newset))) {
> > +	sigdelset(&oldset, SIGTRAP);
> > +	sigdelset(&newset, SIGTRAP);

SIG_TRAP is used by ptrace and will be unblocked.

> > +	if (memcmp(&newset, &oldset, sizeof(newset))) {
> >  		fail("The signal blocking mask was changed");
> >  		numsig = INT_MAX;
> >  	}
> > @@ -161,6 +166,9 @@ int main(int argc, char ** argv)
> >  	pthread_t pthrd;
> >  	int i;
> >  
> > +	memset(&oldset, 0, sizeof(oldset));
> > +	memset(&newset, 0, sizeof(oldset));
> > +
> >  	test_init(argc, argv);
> >  	pthread_mutex_init(&exit_lock, NULL);
> >  	pthread_mutex_lock(&exit_lock);
> > @@ -182,7 +190,7 @@ int main(int argc, char ** argv)
> >  		return -1;
> >  	}
> >  
> > -	if (sigprocmask(SIG_BLOCK, &oldset, NULL) == -1) {
> > +	if (sigprocmask(SIG_BLOCK, NULL, &oldset) == -1) {

A current mask will be saved in a third argument

> >  		err("sigprocmask");
> >  		return -1;
> >  	}
> > @@ -242,7 +250,9 @@ int main(int argc, char ** argv)
> >  	pthread_mutex_unlock(&exit_lock);
> >  	pthread_join(pthrd, NULL);
> >  
> > -	if (!memcmp(&newset, &oldset, sizeof(newset))) {
> > +	sigdelset(&oldset, SIGTRAP);
> > +	sigdelset(&newset, SIGTRAP);
> > +	if (memcmp(&newset, &oldset, sizeof(newset))) {

memcmp(&newset, &oldset, sizeof(newset) returns 0 is masks are equal.

> >  		fail("The signal blocking mask was changed");
> >  		return 1;
> >  	}
> > 
> 
>