none/tests/ppoll_alarm.c

   1 /* Tries to exploit bug in ppoll mask handling:
   2    https://bugs.kde.org/show_bug.cgi?id=359871
   3    where client program was able to successfully block VG_SIGVGKILL. */
   4
   5 #define _GNU_SOURCE /* for ppoll */
   6 #include <poll.h>
   7 #include <pthread.h>
   8 #include <signal.h>
   9 #include <stdio.h>
  10 #include <unistd.h>
  11
  12 static int ready = 0;
  13 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
  14 static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
  15
  16 static void *
  17 mythr(void *ignore)
  18 {
  19     pthread_mutex_lock(&mutex);
  20     ready = 1;
  21     pthread_cond_signal(&cond);
  22     pthread_mutex_unlock(&mutex);
  23
  24     sigset_t ss;
  25     sigfillset(&ss);
  26     while (1) {
  27         struct timespec ts = {10000, 0};
  28         ppoll(NULL, 0, &ts, &ss);
  29     }
  30
  31     return NULL;
  32 }
  33
  34 int
  35 main()
  36 {
  37     pthread_t thr;
  38     int ret = pthread_create(&thr, NULL, mythr, NULL);
  39     if (ret != 0) {
  40         fprintf(stderr, "pthread_create failed\n");
  41         return 1;
  42     }
  43
  44     pthread_mutex_lock(&mutex);
  45     while (ready == 0) {
  46         pthread_cond_wait(&cond, &mutex);
  47     }
  48     pthread_mutex_unlock(&mutex);
  49
  50     alarm(1); /* Unhandled SIGALRM should cause exit. */
  51     while (1)
  52         sleep(1);
  53
  54     return 0;
  55 }