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