1 /* Stack protector support.
2 Copyright (C) 2005 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 2, 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 You should have received a copy of the GNU General Public License
26 along with GCC; see the file COPYING. If not, write to the Free
27 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
30 /* As a special exception, if you link this library with files compiled with
31 GCC to produce an executable, this does not cause the resulting executable
32 to be covered by the GNU General Public License. This exception does not
33 however invalidate any other reasons why the executable file might be
34 covered by the GNU General Public License. */
53 /* Native win32 apps don't know about /dev/tty but can print directly
54 to the console using "CONOUT$" */
55 #if defined (_WIN32) && !defined (__CYGWIN__)
56 # define _PATH_TTY "CONOUT$"
58 # define _PATH_TTY "/dev/tty"
65 void *__stack_chk_guard
= 0;
67 static void __attribute__ ((constructor
))
73 if (__stack_chk_guard
!= 0)
76 fd
= open ("/dev/urandom", O_RDONLY
);
79 ssize_t size
= read (fd
, &__stack_chk_guard
,
80 sizeof (__stack_chk_guard
));
82 if (size
== sizeof(__stack_chk_guard
) && __stack_chk_guard
!= 0)
86 /* If a random generator can't be used, the protector switches the guard
87 to the "terminator canary". */
88 p
= (unsigned char *) &__stack_chk_guard
;
89 p
[sizeof(__stack_chk_guard
)-1] = 255;
90 p
[sizeof(__stack_chk_guard
)-2] = '\n';
95 fail (const char *msg1
, size_t msg1len
, const char *msg3
)
97 #ifdef __GNU_LIBRARY__
98 extern char * __progname
;
100 static const char __progname
[] = "";
104 /* Print error message directly to the tty. This avoids Bad Things
105 happening if stderr is redirected. */
106 fd
= open (_PATH_TTY
, O_WRONLY
);
109 static const char msg2
[] = " terminated\n";
110 size_t progname_len
, len
;
113 progname_len
= strlen (__progname
);
114 len
= msg1len
+ progname_len
+ sizeof(msg2
)-1 + 1;
115 p
= buf
= alloca (len
);
117 memcpy (p
, msg1
, msg1len
);
119 memcpy (p
, __progname
, progname_len
);
121 memcpy (p
, msg2
, sizeof(msg2
));
125 ssize_t wrote
= write (fd
, buf
, len
);
135 /* Only send the error to syslog if there was no tty available. */
137 syslog (LOG_CRIT
, msg3
);
138 #endif /* HAVE_SYSLOG_H */
140 /* Try very hard to exit. Note that signals may be blocked preventing
141 the first two options from working. The use of volatile is here to
142 prevent optimizers from "knowing" that __builtin_trap is called first,
143 and that it doesn't return, and so "obviously" the rest of the code
147 for (state
= 0; ; state
++)
154 *(volatile int *)-1L = 0;
164 __stack_chk_fail (void)
166 const char *msg
= "*** stack smashing detected ***: ";
167 fail (msg
, strlen (msg
), "stack smashing detected: terminated");
173 const char *msg
= "*** buffer overflow detected ***: ";
174 fail (msg
, strlen (msg
), "buffer overflow detected: terminated");
177 #ifdef HAVE_HIDDEN_VISIBILITY
179 __attribute__((visibility ("hidden")))
180 __stack_chk_fail_local (void)