1 /* Stack protector support.
2 Copyright (C) 2005, 2009 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 In addition to the permissions in the GNU General Public License, the
12 Free Software Foundation gives you unlimited permission to link the
13 compiled version of this file into combinations with other programs,
14 and to distribute those combinations without any restriction coming
15 from the use of this file. (The General Public License restrictions
16 do apply in other respects; for example, they cover modification of
17 the file, and distribution when not linked into a combine
20 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
21 WARRANTY; without even the implied warranty of MERCHANTABILITY or
22 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
25 Under Section 7 of GPL version 3, you are granted additional
26 permissions described in the GCC Runtime Library Exception, version
27 3.1, as published by the Free Software Foundation.
29 You should have received a copy of the GNU General Public License and
30 a copy of the GCC Runtime Library Exception along with this program;
31 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
32 <http://www.gnu.org/licenses/>. */
57 /* Native win32 apps don't know about /dev/tty but can print directly
58 to the console using "CONOUT$" */
59 #if defined (_WIN32) && !defined (__CYGWIN__)
60 # define _PATH_TTY "CONOUT$"
62 # define _PATH_TTY "/dev/tty"
69 void *__stack_chk_guard = 0;
71 static void __attribute__ ((constructor))
77 if (__stack_chk_guard != 0)
80 fd = open ("/dev/urandom", O_RDONLY);
83 ssize_t size = read (fd, &__stack_chk_guard,
84 sizeof (__stack_chk_guard));
86 if (size == sizeof(__stack_chk_guard) && __stack_chk_guard != 0)
90 /* If a random generator can't be used, the protector switches the guard
91 to the "terminator canary". */
92 p = (unsigned char *) &__stack_chk_guard;
93 p[sizeof(__stack_chk_guard)-1] = 255;
94 p[sizeof(__stack_chk_guard)-2] = '\n';
99 fail (const char *msg1, size_t msg1len, const char *msg3)
101 #ifdef __GNU_LIBRARY__
102 extern char * __progname;
104 static const char __progname[] = "";
108 /* Print error message directly to the tty. This avoids Bad Things
109 happening if stderr is redirected. */
110 fd = open (_PATH_TTY, O_WRONLY);
113 static const char msg2[] = " terminated\n";
114 size_t progname_len, len;
117 progname_len = strlen (__progname);
118 len = msg1len + progname_len + sizeof(msg2)-1 + 1;
119 p = buf = alloca (len);
121 memcpy (p, msg1, msg1len);
123 memcpy (p, __progname, progname_len);
125 memcpy (p, msg2, sizeof(msg2));
129 ssize_t wrote = write (fd, buf, len);
139 /* Only send the error to syslog if there was no tty available. */
141 syslog (LOG_CRIT, msg3);
142 #endif /* HAVE_SYSLOG_H */
144 /* Try very hard to exit. Note that signals may be blocked preventing
145 the first two options from working. The use of volatile is here to
146 prevent optimizers from "knowing" that __builtin_trap is called first,
147 and that it doesn't return, and so "obviously" the rest of the code
151 for (state = 0; ; state++)
158 *(volatile int *)-1L = 0;
168 __stack_chk_fail (void)
170 const char *msg = "*** stack smashing detected ***: ";
171 fail (msg, strlen (msg), "stack smashing detected: terminated");
177 const char *msg = "*** buffer overflow detected ***: ";
178 fail (msg, strlen (msg), "buffer overflow detected: terminated");
181 #ifdef HAVE_HIDDEN_VISIBILITY
183 __attribute__((visibility ("hidden")))
184 __stack_chk_fail_local (void)