1 /* Test that stack overflow and SIGSEGV are correctly distinguished.
2 Copyright (C) 2002-2023 Free Software Foundation, Inc.
3
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
16
17 /* Written by Bruno Haible and Eric Blake. */
18
19 #include <config.h>
20
21 /* Specification. */
22 #include "sigsegv.h"
23
24 #include <stdint.h>
25 #include <stdio.h>
26 #include <limits.h>
27
28 #if HAVE_STACK_OVERFLOW_RECOVERY && HAVE_SIGSEGV_RECOVERY
29
30 # if defined _WIN32 && !defined __CYGWIN__
31 /* Windows doesn't have sigset_t. */
32 typedef int sigset_t;
33 # define sigemptyset(set)
34 # define sigprocmask(how,set,oldset)
35 # endif
36
37 # include "mmap-anon-util.h"
38 # include <stddef.h> /* needed for NULL on SunOS4 */
39 # include <stdlib.h> /* for abort, exit */
40 # include <signal.h>
41 # include <setjmp.h>
42 # if HAVE_SETRLIMIT
43 # include <sys/types.h>
44 # include <sys/time.h>
45 # include <sys/resource.h>
46 # endif
47 # include "altstack-util.h"
48
49 static jmp_buf mainloop;
50 static sigset_t mainsigset;
51
52 static volatile int pass = 0;
53 static uintptr_t page;
54 static volatile int *null_pointer_to_volatile_int /* = NULL */;
55
56 static void
57 stackoverflow_handler_continuation (void *arg1, void *arg2, void *arg3)
58 {
59 int arg = (int) (long) arg1;
60 longjmp (mainloop, arg);
61 }
62
63 static void
64 stackoverflow_handler (int emergency, stackoverflow_context_t scp)
65 {
66 pass++;
67 if (pass <= 2)
68 printf ("Stack overflow %d caught.\n", pass);
69 else
70 {
71 printf ("Segmentation violation misdetected as stack overflow.\n");
72 exit (1);
73 }
74 sigprocmask (SIG_SETMASK, &mainsigset, NULL);
75 sigsegv_leave_handler (stackoverflow_handler_continuation,
76 (void *) (long) (emergency ? -1 : pass), NULL, NULL);
77 }
78
79 static int
80 sigsegv_handler (void *address, int emergency)
81 {
82 /* This test is necessary to distinguish stack overflow and SIGSEGV. */
83 if (!emergency)
84 return 0;
85
86 pass++;
87 if (pass <= 2)
88 {
89 printf ("Stack overflow %d missed.\n", pass);
90 exit (1);
91 }
92 else
93 printf ("Segmentation violation correctly detected.\n");
94 sigprocmask (SIG_SETMASK, &mainsigset, NULL);
95 return sigsegv_leave_handler (stackoverflow_handler_continuation,
96 (void *) (long) pass, NULL, NULL);
97 }
98
99 static volatile int *
100 recurse_1 (int n, volatile int *p)
101 {
102 if (n < INT_MAX)
103 *recurse_1 (n + 1, p) += n;
104 return p;
105 }
106
107 static int
108 recurse (volatile int n)
109 {
110 return *recurse_1 (n, &n);
111 }
112
113 int
114 main ()
115 {
116 int prot_unwritable;
117 void *p;
118 sigset_t emptyset;
119
120 # if HAVE_SETRLIMIT && defined RLIMIT_STACK
121 /* Before starting the endless recursion, try to be friendly to the user's
122 machine. On some Linux 2.2.x systems, there is no stack limit for user
123 processes at all. We don't want to kill such systems. */
124 struct rlimit rl;
125 rl.rlim_cur = rl.rlim_max = 0x100000; /* 1 MB */
126 setrlimit (RLIMIT_STACK, &rl);
127 # endif
128
129 /* Prepare the storage for the alternate stack. */
130 prepare_alternate_stack ();
131
132 /* Install the stack overflow handler. */
133 if (stackoverflow_install_handler (&stackoverflow_handler,
134 mystack, MYSTACK_SIZE)
135 < 0)
136 exit (2);
137
138 /* Preparations. */
139 # if !HAVE_MAP_ANONYMOUS
140 zero_fd = open ("/dev/zero", O_RDONLY, 0644);
141 # endif
142
143 # if defined __linux__ && defined __sparc__
144 /* On Linux 2.6.26/SPARC64, PROT_READ has the same effect as
145 PROT_READ | PROT_WRITE. */
146 prot_unwritable = PROT_NONE;
147 # else
148 prot_unwritable = PROT_READ;
149 # endif
150
151 /* Setup some mmaped memory. */
152 p = mmap_zeromap ((void *) 0x12340000, 0x4000);
153 if (p == (void *)(-1))
154 {
155 fprintf (stderr, "mmap_zeromap failed.\n");
156 exit (2);
157 }
158 page = (uintptr_t) p;
159
160 /* Make it read-only. */
161 if (mprotect ((void *) page, 0x4000, prot_unwritable) < 0)
162 {
163 fprintf (stderr, "mprotect failed.\n");
164 exit (2);
165 }
166
167 /* Install the SIGSEGV handler. */
168 if (sigsegv_install_handler (&sigsegv_handler) < 0)
169 exit (2);
170
171 /* Save the current signal mask. */
172 sigemptyset (&emptyset);
173 sigprocmask (SIG_BLOCK, &emptyset, &mainsigset);
174
175 /* Provoke two stack overflows in a row. */
176 switch (setjmp (mainloop))
177 {
178 case -1:
179 printf ("emergency exit\n"); exit (1);
180 case 0: case 1:
181 printf ("Starting recursion pass %d.\n", pass + 1);
182 recurse (0);
183 printf ("no endless recursion?!\n"); exit (1);
184 case 2:
185 *(volatile int *) (page + 0x678) = 42;
186 break;
187 case 3:
188 *null_pointer_to_volatile_int = 42;
189 break;
190 case 4:
191 break;
192 default:
193 abort ();
194 }
195
196 /* Validate that the alternate stack did not overflow. */
197 check_alternate_stack_no_overflow ();
198
199 printf ("Test passed.\n");
200 exit (0);
201 }
202
203 #else
204
205 int
206 main ()
207 {
208 return 77;
209 }
210
211 #endif