/* Test program for making nonexecutable stacks executable on load of a DSO that requires executable stacks. */ #include <dlfcn.h> #include <stdio.h> #include <string.h> #include <unistd.h> #include <error.h> static void print_maps (void) { #if 0 char *cmd = NULL; asprintf (&cmd, "cat /proc/%d/maps", getpid ()); system (cmd); free (cmd); #endif } static void deeper (void (*f) (void)); #if USE_PTHREADS # include <pthread.h> static void * tryme_thread (void *f) { (*((void (*) (void)) f)) (); return 0; } static pthread_barrier_t startup_barrier, go_barrier; static void * waiter_thread (void *arg) { void **f = arg; pthread_barrier_wait (&startup_barrier); pthread_barrier_wait (&go_barrier); (*((void (*) (void)) *f)) (); return 0; } #endif static int do_test (void) { void *f; #if USE_PTHREADS /* Create some threads while stacks are nonexecutable. */ #define N 5 pthread_t thr[N]; pthread_barrier_init (&startup_barrier, NULL, N + 1); pthread_barrier_init (&go_barrier, NULL, N + 1); for (int i = 0; i < N; ++i) { int rc = pthread_create (&thr[i], NULL, &waiter_thread, &f); if (rc) error (1, rc, "pthread_create"); } /* Make sure they are all there using their stacks. */ pthread_barrier_wait (&startup_barrier); puts ("threads waiting"); #endif print_maps (); /* Loading this module should force stacks to become executable. */ void *h = dlopen ("tst-execstack-mod.so", RTLD_LAZY); if (h == NULL) { printf ("cannot load: %s\n", dlerror ()); return 1; } f = dlsym (h, "tryme"); if (f == NULL) { printf ("symbol not found: %s\n", dlerror ()); return 1; } /* Test if that really made our stack executable. The `tryme' function should crash if not. */ (*((void (*) (void)) f)) (); print_maps (); /* Test that growing the stack region gets new executable pages too. */ deeper ((void (*) (void)) f); print_maps (); #if USE_PTHREADS /* Test that a fresh thread now gets an executable stack. */ { pthread_t th; int rc = pthread_create (&th, NULL, &tryme_thread, f); if (rc) error (1, rc, "pthread_create"); } puts ("threads go"); /* The existing threads' stacks should have been changed. Let them run to test it. */ pthread_barrier_wait (&go_barrier); pthread_exit (0); #endif return 0; } static void deeper (void (*f) (void)) { char stack[1100 * 1024]; memfrob (stack, sizeof stack); (*f) (); memfrob (stack, sizeof stack); } #define TEST_FUNCTION do_test () #include "../test-skeleton.c"