1 /* Verify longjmp fortify checking does not reject signal stacks. */
2 #include <assert.h>
3 #include <setjmp.h>
4 #include <signal.h>
5 #include <stdio.h>
6 #include <stdlib.h>
7 #include <string.h>
8 #include <sys/types.h>
9 #include <sys/time.h>
10 #include <sys/resource.h>
11 #include <unistd.h>
12
13 static int do_test (void);
14 #define TEST_FUNCTION do_test ()
15 #include "../test-skeleton.c"
16
17 static jmp_buf mainloop;
18 static sigset_t mainsigset;
19 static volatile sig_atomic_t pass;
20
21 static void
write_indented(const char * str)22 write_indented (const char *str)
23 {
24 for (int i = 0; i < pass; ++i)
25 write_message (" ");
26 write_message (str);
27 }
28
29 static void
stackoverflow_handler(int sig)30 stackoverflow_handler (int sig)
31 {
32 stack_t altstack;
33 /* Sanity check to keep test from looping forever (in case the longjmp
34 chk code is slightly broken). */
35 pass++;
36 sigaltstack (NULL, &altstack);
37 write_indented ("in signal handler\n");
38 if (altstack.ss_flags & SS_ONSTACK)
39 write_indented ("on alternate stack\n");
40 siglongjmp (mainloop, pass);
41 }
42
43
44 static volatile int *
recurse_1(int n,volatile int * p)45 recurse_1 (int n, volatile int *p)
46 {
47 if (n >= 0)
48 *recurse_1 (n + 1, p) += n;
49 return p;
50 }
51
52
53 static int
recurse(int n)54 recurse (int n)
55 {
56 int sum = 0;
57 return *recurse_1 (n, &sum);
58 }
59
60
61 static int
do_test(void)62 do_test (void)
63 {
64 char mystack[SIGSTKSZ];
65 stack_t altstack;
66 struct sigaction action;
67 sigset_t emptyset;
68 /* Before starting the endless recursion, try to be friendly to the user's
69 machine. On some Linux 2.2.x systems, there is no stack limit for user
70 processes at all. We don't want to kill such systems. */
71 struct rlimit rl;
72 rl.rlim_cur = rl.rlim_max = 0x100000; /* 1 MB */
73 setrlimit (RLIMIT_STACK, &rl);
74 /* Install the alternate stack. */
75 altstack.ss_sp = mystack;
76 altstack.ss_size = sizeof (mystack);
77 altstack.ss_flags = 0; /* no SS_DISABLE */
78 if (sigaltstack (&altstack, NULL) < 0)
79 {
80 puts ("first sigaltstack failed");
81 return 0;
82 }
83 /* Install the SIGSEGV handler. */
84 sigemptyset (&action.sa_mask);
85 action.sa_handler = &stackoverflow_handler;
86 action.sa_flags = SA_ONSTACK;
87 sigaction (SIGSEGV, &action, (struct sigaction *) NULL);
88 sigaction (SIGBUS, &action, (struct sigaction *) NULL);
89
90 /* Save the current signal mask. */
91 sigemptyset (&emptyset);
92 sigprocmask (SIG_BLOCK, &emptyset, &mainsigset);
93
94 /* Provoke two stack overflows in a row. */
95 if (sigsetjmp (mainloop, 1) != 0)
96 {
97 assert (pass != 0);
98 printf ("%*sout of signal handler\n", pass, "");
99 }
100 else
101 assert (pass == 0);
102
103 sigaltstack (NULL, &altstack);
104 if (altstack.ss_flags & SS_ONSTACK)
105 printf ("%*son alternate stack\n", pass, "");
106 else
107 printf ("%*snot on alternate stack\n", pass, "");
108
109 if (pass < 2)
110 {
111 recurse (0);
112 puts ("recurse call returned");
113 return 2;
114 }
115
116 altstack.ss_flags |= SS_DISABLE;
117 if (sigaltstack (&altstack, NULL) == -1)
118 printf ("disabling alternate stack failed\n");
119 else
120 printf ("disabling alternate stack succeeded \n");
121
122 /* Restore the signal handlers, in case we trigger a crash after the
123 tests above. */
124 signal (SIGBUS, SIG_DFL);
125 signal (SIGSEGV, SIG_DFL);
126
127 return 0;
128 }
129