compiler-rt/test/safestack/pthread-cleanup.c

   1 // RUN: %clang_safestack %s -pthread -o %t
   2 // RUN: %run %t 0
   3 // RUN: not --crash %run %t 1
   4
   5 // Test unsafe stack deallocation. Unsafe stacks are not deallocated immediately
   6 // at thread exit. They are deallocated by following exiting threads.
   7
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <pthread.h>
  11
  12 enum { kBufferSize = (1 << 15) };
  13
  14 void *start(void *ptr)
  15 {
  16   char buffer[kBufferSize];
  17   return buffer;
  18 }
  19
  20 extern unsigned sleep(unsigned seconds);
  21
  22 int main(int argc, char **argv)
  23 {
  24   int arg = atoi(argv[1]);
  25
  26   pthread_t t1, t2;
  27   char *t1_buffer = NULL;
  28
  29   if (pthread_create(&t1, NULL, start, NULL))
  30     abort();
  31   if (pthread_join(t1, &t1_buffer))
  32     abort();
  33
  34   // Stack has not yet been deallocated
  35   memset(t1_buffer, 0, kBufferSize);
  36
  37   if (arg == 0)
  38     return 0;
  39
  40   for (int i = 0; i < 3; i++) {
  41     if (pthread_create(&t2, NULL, start, NULL))
  42       abort();
  43     // Second thread destructor cleans up the first thread's stack.
  44     if (pthread_join(t2, NULL))
  45       abort();
  46
  47     // Should segfault here
  48     memset(t1_buffer, 0, kBufferSize);
  49
  50     // PR39001: Re-try in the rare case that pthread_join() returns before the
  51     // thread finishes exiting in the kernel--hence the tgkill() check for t1
  52     // returns that it's alive despite pthread_join() returning.
  53     sleep(1);
  54   }
  55   return 0;
  56 }