debug/tst-longjmp_chk2.c

   1 /* Verify longjmp fortify checking does not reject signal stacks.
   2
   3    Test case mostly written by Paolo Bonzini <pbonzini@redhat.com>.  */
   4 #include <assert.h>
   5 #include <setjmp.h>
   6 #include <signal.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <sys/types.h>
  10 #include <sys/time.h>
  11 #include <sys/resource.h>
  12
  13
  14 static jmp_buf mainloop;
  15 static sigset_t mainsigset;
  16 static int pass;
  17
  18
  19 static void
  20 stackoverflow_handler (int sig)
  21 {
  22   stack_t altstack;
  23   /* Sanity check to keep test from looping forever (in case the longjmp
  24      chk code is slightly broken).  */
  25   pass++;
  26   assert (pass < 5);
  27   sigaltstack (NULL, &altstack);
  28   /* Using printf is not really kosher in signal handlers but we know
  29      it will work.  */
  30   printf ("%*sin signal handler\n", pass, "");
  31   if (altstack.ss_flags & SS_ONSTACK)
  32     printf ("%*son alternate stack\n", pass, "");
  33   siglongjmp (mainloop, pass);
  34 }
  35
  36
  37 static volatile int *
  38 recurse_1 (int n, volatile int *p)
  39 {
  40   if (n >= 0)
  41     *recurse_1 (n + 1, p) += n;
  42   return p;
  43 }
  44
  45
  46 static int
  47 recurse (int n)
  48 {
  49   int sum = 0;
  50   return *recurse_1 (n, &sum);
  51 }
  52
  53
  54 static int
  55 do_test (void)
  56 {
  57   char mystack[SIGSTKSZ];
  58   stack_t altstack;
  59   struct sigaction action;
  60   sigset_t emptyset;
  61   /* Before starting the endless recursion, try to be friendly to the user's
  62      machine.  On some Linux 2.2.x systems, there is no stack limit for user
  63      processes at all.  We don't want to kill such systems.  */
  64   struct rlimit rl;
  65   rl.rlim_cur = rl.rlim_max = 0x100000; /* 1 MB */
  66   setrlimit (RLIMIT_STACK, &rl);
  67   /* Install the alternate stack.  */
  68   altstack.ss_sp = mystack;
  69   altstack.ss_size = sizeof (mystack);
  70   altstack.ss_flags = 0; /* no SS_DISABLE */
  71   if (sigaltstack (&altstack, NULL) < 0)
  72     {
  73       puts ("first sigaltstack failed");
  74       return 0;
  75     }
  76   /* Install the SIGSEGV handler.  */
  77   sigemptyset (&action.sa_mask);
  78   action.sa_handler = &stackoverflow_handler;
  79   action.sa_flags = SA_ONSTACK;
  80   sigaction (SIGSEGV, &action, (struct sigaction *) NULL);
  81   sigaction (SIGBUS, &action, (struct sigaction *) NULL);
  82
  83   /* Save the current signal mask.  */
  84   sigemptyset (&emptyset);
  85   sigprocmask (SIG_BLOCK, &emptyset, &mainsigset);
  86
  87   /* Provoke two stack overflows in a row.  */
  88   if (sigsetjmp (mainloop, 1) != 0)
  89     {
  90       assert (pass != 0);
  91       printf ("%*sout of signal handler\n", pass, "");
  92     }
  93   else
  94     assert (pass == 0);
  95
  96   sigaltstack (NULL, &altstack);
  97   if (altstack.ss_flags & SS_ONSTACK)
  98     printf ("%*son alternate stack\n", pass, "");
  99   else
 100     printf ("%*snot on alternate stack\n", pass, "");
 101
 102   if (pass < 2)
 103     {
 104       recurse (0);
 105       puts ("recurse call returned");
 106       return 2;
 107     }
 108
 109   altstack.ss_flags |= SS_DISABLE;
 110   if (sigaltstack (&altstack, NULL) == -1)
 111     printf ("disabling alternate stack failed\n");
 112   else
 113     printf ("disabling alternate stack succeeded \n");
 114
 115   return 0;
 116 }
 117
 118 #define TEST_FUNCTION do_test ()
 119 #include "../test-skeleton.c"