mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-29 05:51:10 +00:00
d40ac01cbb
The recursive lock used on abort does not synchronize with a new process
creation (either by fork-like interfaces or posix_spawn ones), nor it
is reinitialized after fork().
Also, the SIGABRT unblock before raise() shows another race condition,
where a fork or posix_spawn() call by another thread, just after the
recursive lock release and before the SIGABRT signal, might create
programs with a non-expected signal mask. With the default option
(without POSIX_SPAWN_SETSIGDEF), the process can see SIG_DFL for
SIGABRT, where it should be SIG_IGN.
To fix the AS-safe, raise() does not change the process signal mask,
and an AS-safe lock is used if a SIGABRT is installed or the process
is blocked or ignored. With the signal mask change removal,
there is no need to use a recursive loc. The lock is also taken on
both _Fork() and posix_spawn(), to avoid the spawn process to see the
abort handler as SIG_DFL.
A read-write lock is used to avoid serialize _Fork and posix_spawn
execution. Both sigaction (SIGABRT) and abort() requires to lock
as writer (since both change the disposition).
The fallback is also simplified: there is no need to use a loop of
ABORT_INSTRUCTION after _exit() (if the syscall does not terminate the
process, the system is broken).
The proposed fix changes how setjmp works on a SIGABRT handler, where
glibc does not save the signal mask. So usage like the below will now
always abort.
static volatile int chk_fail_ok;
static jmp_buf chk_fail_buf;
static void
handler (int sig)
{
if (chk_fail_ok)
{
chk_fail_ok = 0;
longjmp (chk_fail_buf, 1);
}
else
_exit (127);
}
[...]
signal (SIGABRT, handler);
[....]
chk_fail_ok = 1;
if (! setjmp (chk_fail_buf))
{
// Something that can calls abort, like a failed fortify function.
chk_fail_ok = 0;
printf ("FAIL\n");
}
Such cases will need to use sigsetjmp instead.
The _dl_start_profile calls sigaction through _profil, and to avoid
pulling abort() on loader the call is replaced with __libc_sigaction.
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
48 lines
1.4 KiB
C
48 lines
1.4 KiB
C
/* Copyright (C) 1991-2024 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library 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
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <errno.h>
|
|
#include <internal-signals.h>
|
|
#include <libc-lock.h>
|
|
#include <signal.h>
|
|
|
|
/* If ACT is not NULL, change the action for SIG to *ACT.
|
|
If OACT is not NULL, put the old action for SIG in *OACT. */
|
|
int
|
|
__sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
|
|
{
|
|
if (sig <= 0 || sig >= NSIG || is_internal_signal (sig))
|
|
{
|
|
__set_errno (EINVAL);
|
|
return -1;
|
|
}
|
|
|
|
internal_sigset_t set;
|
|
|
|
if (sig == SIGABRT)
|
|
__abort_lock_wrlock (&set);
|
|
|
|
int r = __libc_sigaction (sig, act, oact);
|
|
|
|
if (sig == SIGABRT)
|
|
__abort_lock_unlock (&set);
|
|
|
|
return r;
|
|
}
|
|
libc_hidden_def (__sigaction)
|
|
weak_alias (__sigaction, sigaction)
|