1 /* Make sure longjmp fortification catches bad signal stacks.
2 Copyright (C) 2013-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <setjmp.h>
20 #include <signal.h>
21 #include <string.h>
22
23 static int do_test (void);
24 #define TEST_FUNCTION do_test ()
25 #include "../test-skeleton.c"
26
27 static char buf[SIGSTKSZ * 4];
28 static jmp_buf jb;
29
30 static void
handler(int sig)31 handler (int sig)
32 {
33 if (sig == SIGUSR1)
34 {
35 if (setjmp (jb) != 0)
36 {
37 puts ("setjmp should not have been called");
38 kill (getpid (), SIGTERM);
39 }
40 }
41 else if (sig == SIGABRT)
42 {
43 /* Yeah it worked. */
44 _exit (0);
45 }
46 }
47
48 static int
do_test(void)49 do_test (void)
50 {
51 stack_t ss;
52
53 set_fortify_handler (handler);
54
55 /* Create a valid signal stack and enable it. */
56 ss.ss_sp = buf;
57 ss.ss_size = sizeof (buf);
58 ss.ss_flags = 0;
59 if (sigaltstack (&ss, NULL) < 0)
60 {
61 printf ("first sigaltstack failed: %m\n");
62 return 1;
63 }
64
65 /* Trigger the signal handler which will create a jmpbuf that points to the
66 end of the signal stack. */
67 signal (SIGUSR1, handler);
68 kill (getpid (), SIGUSR1);
69
70 /* Shrink the signal stack so the jmpbuf is now invalid.
71 We adjust the start & end to handle stacks that grow up & down. */
72 ss.ss_sp = buf + sizeof (buf) / 2;
73 ss.ss_size = sizeof (buf) / 4;
74 if (sigaltstack (&ss, NULL) < 0)
75 {
76 printf ("second sigaltstack failed: %m\n");
77 return 1;
78 }
79
80 /* This should fail. */
81 longjmp (jb, 1);
82
83 puts ("longjmp returned and shouldn't");
84 return 1;
85 }
86