1 /* Copyright (C) 2011-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library 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 GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library. If not, see
16 <https://www.gnu.org/licenses/>. */
17
18 #include <jmpbuf-offsets.h>
19 #include <sysdep.h>
20 #include <setjmp.h>
21 #include <signal.h>
22 #include <stdio.h>
23 #include <stackinfo.h>
24
25 #ifdef _STACK_GROWS_DOWN
26 #define called_from(this, saved) ((this) < (saved))
27 #else
28 #define called_from(this, saved) ((this) > (saved))
29 #endif
30
31 extern void ____longjmp_chk (__jmp_buf __env, int __val)
32 __attribute__ ((__noreturn__));
33
____longjmp_chk(__jmp_buf env,int val)34 void ____longjmp_chk (__jmp_buf env, int val)
35 {
36 void *this_frame = __builtin_frame_address (0);
37 void *saved_frame = JB_FRAME_ADDRESS (env);
38 stack_t ss;
39
40 /* If "env" is from a frame that called us, we're all set. */
41 if (called_from(this_frame, saved_frame))
42 __longjmp (env, val);
43
44 /* If we can't get the current stack state, give up and do the longjmp. */
45 if (INTERNAL_SYSCALL_CALL (sigaltstack, NULL, &ss) != 0)
46 __longjmp (env, val);
47
48 /* If we we are executing on the alternate stack and within the
49 bounds, do the longjmp. */
50 if (ss.ss_flags == SS_ONSTACK
51 && (this_frame >= ss.ss_sp && this_frame < (ss.ss_sp + ss.ss_size)))
52 __longjmp (env, val);
53
54 __fortify_fail ("longjmp causes uninitialized stack frame");
55 }
56