Date: Sat, 24 Aug 2019 23:41:14 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Trond =?utf-8?Q?Endrest=C3=B8l?= <trond.endrestol@ximalas.info> Cc: freebsd-stable@freebsd.org Subject: Re: ntpd doesn't like ASLR on stable/12 post-r350672 Message-ID: <20190824204114.GG71821@kib.kiev.ua> In-Reply-To: <alpine.BSF.2.21.99999.352.1908242135380.6386@enterprise.ximalas.info> References: <alpine.BSF.2.21.99999.352.1908242135380.6386@enterprise.ximalas.info>
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On Sat, Aug 24, 2019 at 10:04:49PM +0200, Trond Endrestøl wrote:
> Hi,
>
> I'm running stable/12 with ASLR enabled in /etc/sysctl.conf:
>
> kern.elf64.aslr.enable=1
> kern.elf64.aslr.pie_enable=1
> kern.elf32.aslr.enable=1
> kern.elf32.aslr.pie_enable=1
>
> After upgrading to anything after r350672, now at r351450, ntpd
> refuses to start at boot.
>
> Aug 24 21:25:42 <ntp.notice> HOSTNAME ntpd[5618]: ntpd 4.2.8p12-a (1): Starting
> Aug 24 21:25:43 <kern.info> HOSTNAME kernel: [406] pid 5619 (ntpd), jid 0, uid 123: exited on signal 11
>
> Disabling ASLR, kern.elf64.aslr.enable=0, before starting ntpd
> manually is a workaround, but this is not viable in the long run.
Why ?
>
> I tried changing command="/usr/sbin/${name}" to
> command="/usr/bin/proccontrol -m aslr -s disable /usr/sbin/${name}" in
> /etc/rc.d/ntpd, but that didn't go well.
If you set kern.elf64.aslr.stack_gap to zero, does it help ?
>
> Running ntpd through gdb while ASLR was enabled, I narrowed it down to
> /usr/src/contrib/ntp/ntpd/ntpd.c:1001
>
> ntp_rlimit(RLIMIT_STACK, DFLT_RLIMIT_STACK * 4096, 4096, "4k");
>
> which calls /usr/src/contrib/ntp/ntpd/ntp_config.c:5211 and proceeds
> to /usr/src/contrib/ntp/ntpd/ntp_config.c:5254
>
> if (-1 == getrlimit(RLIMIT_STACK, &rl)) {
>
> Single stepping from this point gave me:
>
> ====
>
> (gdb) s
> _thr_rtld_set_flag (mask=1) at /usr/src/lib/libthr/thread/thr_rtld.c:171
> 171 {
> (gdb)
> 176 return (0);
> (gdb)
> _thr_rtld_rlock_acquire (lock=0x80180d200) at /usr/src/lib/libthr/thread/thr_rtld.c:115
> 115 {
> (gdb)
> 120 curthread = _get_curthread();
> (gdb)
> _get_curthread () at /usr/src/lib/libthr/arch/amd64/include/pthread_md.h:97
> 97 return (TCB_GET64(tcb_thread));
> (gdb)
> _thr_rtld_rlock_acquire (lock=0x80180d200) at /usr/src/lib/libthr/thread/thr_rtld.c:121
> 121 SAVE_ERRNO();
> (gdb)
> 124 THR_CRITICAL_ENTER(curthread);
> (gdb)
> _thr_rwlock_tryrdlock (rwlock=<optimized out>, flags=0) at /usr/src/lib/libthr/thread/thr_umtx.h:192
> 192 (rwlock->rw_flags & URWLOCK_PREFER_READER) != 0)
> (gdb)
> 191 if ((flags & URWLOCK_PREFER_READER) != 0 ||
> (gdb)
> 197 while (!(state & wrflags)) {
> (gdb)
> 201 if (atomic_cmpset_acq_32(&rwlock->rw_state, state, state + 1))
> (gdb)
> atomic_cmpset_int (dst=<optimized out>, expect=<optimized out>, src=1) at /usr/obj/usr/src/amd64.amd64/tmp/usr/include/machine/atomic.h:220
> 220 ATOMIC_CMPSET(int);
> (gdb)
> _thr_rwlock_tryrdlock (rwlock=<optimized out>, flags=0) at /usr/src/lib/libthr/thread/thr_umtx.h:201
> 201 if (atomic_cmpset_acq_32(&rwlock->rw_state, state, state + 1))
> (gdb)
> _thr_rtld_rlock_acquire (lock=0x80180d200) at /usr/src/lib/libthr/thread/thr_rtld.c:127
> 127 curthread->rdlock_count++;
> (gdb)
> 128 RESTORE_ERRNO();
> (gdb)
> 129 }
> (gdb)
> _thr_rtld_clr_flag (mask=1) at /usr/src/lib/libthr/thread/thr_rtld.c:181
> 181 {
> (gdb)
> 182 return (0);
> (gdb)
> _thr_rtld_lock_release (lock=0x80180d200) at /usr/src/lib/libthr/thread/thr_rtld.c:150
> 150 {
> (gdb)
> _get_curthread () at /usr/src/lib/libthr/arch/amd64/include/pthread_md.h:97
> 97 return (TCB_GET64(tcb_thread));
> (gdb)
> _thr_rtld_lock_release (lock=0x80180d200) at /usr/src/lib/libthr/thread/thr_rtld.c:157
> 157 SAVE_ERRNO();
> (gdb)
> 160 state = l->lock.rw_state;
> (gdb)
> 161 if (_thr_rwlock_unlock(&l->lock) == 0) {
> (gdb)
> _thr_rwlock_unlock (rwlock=0x80180d200) at /usr/src/lib/libthr/thread/thr_umtx.h:249
> 249 state = rwlock->rw_state;
> (gdb)
> 250 if ((state & URWLOCK_WRITE_OWNER) != 0) {
> (gdb)
> 256 if (__predict_false(URWLOCK_READER_COUNT(state) == 0))
> (gdb)
> 260 URWLOCK_READER_COUNT(state) == 1))
> {
> (gdb)
> 259 URWLOCK_READ_WAITERS)) != 0 &&
> (gdb)
> 262 state, state - 1))
> (gdb)
> 261 if (atomic_cmpset_rel_32(&rwlock->rw_state,
> (gdb)
> atomic_cmpset_int (dst=<optimized out>, expect=<optimized out>, src=0) at /usr/obj/usr/src/amd64.amd64/tmp/usr/include/machine/atomic.h:220
> 220 ATOMIC_CMPSET(int);
> (gdb)
> _thr_rwlock_unlock (rwlock=0x80180d200) at /usr/src/lib/libthr/thread/thr_umtx.h:261
> 261 if (atomic_cmpset_rel_32(&rwlock->rw_state,
> (gdb)
> _thr_rtld_lock_release (lock=<optimized out>) at /usr/src/lib/libthr/thread/thr_rtld.c:162
> 162 if ((state & URWLOCK_WRITE_OWNER) == 0)
> (gdb)
> 163 curthread->rdlock_count--;
> (gdb)
> 164 THR_CRITICAL_LEAVE(curthread);
> (gdb)
> _thr_ast (curthread=0x80864b000) at /usr/src/lib/libthr/thread/thr_sig.c:271
> 271 if (!THR_IN_CRITICAL(curthread)) {
> (gdb)
> 272 check_deferred_signal(curthread);
> (gdb)
> check_deferred_signal (curthread=0x80864b000) at /usr/src/lib/libthr/thread/thr_sig.c:332
> 332 if (__predict_true(curthread->deferred_siginfo.si_signo == 0 ||
> (gdb)
> 351 }
> (gdb)
> _thr_ast (curthread=0x80864b000) at /usr/src/lib/libthr/thread/thr_sig.c:273
> 273 check_suspend(curthread);
> (gdb)
> check_suspend (curthread=0x80864b000) at /usr/src/lib/libthr/thread/thr_sig.c:358
> 358 if (__predict_true((curthread->flags &
> (gdb)
> 401 }
> (gdb)
> _thr_ast (curthread=0x80864b000) at /usr/src/lib/libthr/thread/thr_sig.c:274
> 274 check_cancel(curthread, NULL);
> (gdb)
> check_cancel (curthread=0x80864b000, ucp=0x0) at /usr/src/lib/libthr/thread/thr_sig.c:283
> 283 if (__predict_true(!curthread->cancel_pending ||
> (gdb)
> _thr_ast (curthread=<optimized out>) at /usr/src/lib/libthr/thread/thr_sig.c:276
> 276 }
> (gdb)
> _thr_rtld_lock_release (lock=<optimized out>) at /usr/src/lib/libthr/thread/thr_rtld.c:166
> 166 RESTORE_ERRNO();
> (gdb)
> 167 }
> (gdb)
> getrlimit () at getrlimit.S:3
> 3 RSYSCALL(getrlimit)
> (gdb)
> ntp_rlimit (rl_what=<optimized out>, rl_value=204800, rl_scale=<optimized out>, rl_sstr=<optimized out>) at /usr/src/contrib/ntp/ntpd/ntp_config.c:5257
> 5257 if (rl_value > rl.rlim_max) {
> (gdb)
> 5264 rl.rlim_cur = rl_value;
> (gdb)
> 5265 if (-1 == setrlimit(RLIMIT_STACK, &rl)) {
> (gdb)
> _thr_rtld_set_flag (mask=1) at /usr/src/lib/libthr/thread/thr_rtld.c:171
> 171 {
> (gdb)
> 176 return (0);
> (gdb)
> _thr_rtld_rlock_acquire (lock=0x80180d200) at /usr/src/lib/libthr/thread/thr_rtld.c:115
> 115 {
> (gdb)
> 120 curthread = _get_curthread();
> (gdb)
> _get_curthread () at /usr/src/lib/libthr/arch/amd64/include/pthread_md.h:97
> 97 return (TCB_GET64(tcb_thread));
> (gdb)
> _thr_rtld_rlock_acquire (lock=0x80180d200) at /usr/src/lib/libthr/thread/thr_rtld.c:121
> 121 SAVE_ERRNO();
> (gdb)
> 124 THR_CRITICAL_ENTER(curthread);
> (gdb)
> _thr_rwlock_tryrdlock (rwlock=<optimized out>, flags=0) at /usr/src/lib/libthr/thread/thr_umtx.h:192
> 192 (rwlock->rw_flags & URWLOCK_PREFER_READER) != 0)
> (gdb)
> 191 if ((flags & URWLOCK_PREFER_READER) != 0 ||
> (gdb)
> 197 while (!(state & wrflags)) {
> (gdb)
> 201 if (atomic_cmpset_acq_32(&rwlock->rw_state, state, state + 1))
> (gdb)
> atomic_cmpset_int (dst=<optimized out>, expect=<optimized out>, src=1) at /usr/obj/usr/src/amd64.amd64/tmp/usr/include/machine/atomic.h:220
> 220 ATOMIC_CMPSET(int);
> (gdb)
> _thr_rwlock_tryrdlock (rwlock=<optimized out>, flags=0) at /usr/src/lib/libthr/thread/thr_umtx.h:201
> 201 if (atomic_cmpset_acq_32(&rwlock->rw_state, state, state + 1))
> (gdb)
> _thr_rtld_rlock_acquire (lock=0x80180d200) at /usr/src/lib/libthr/thread/thr_rtld.c:127
> 127 curthread->rdlock_count++;
> (gdb)
> 128 RESTORE_ERRNO();
> (gdb)
> 129 }
> (gdb)
> _thr_rtld_clr_flag (mask=1) at /usr/src/lib/libthr/thread/thr_rtld.c:181
> 181 {
> (gdb)
> 182 return (0);
> (gdb)
> _thr_rtld_lock_release (lock=0x80180d200) at /usr/src/lib/libthr/thread/thr_rtld.c:150
> 150 {
> (gdb)
> _get_curthread () at /usr/src/lib/libthr/arch/amd64/include/pthread_md.h:97
> 97 return (TCB_GET64(tcb_thread));
> (gdb)
> _thr_rtld_lock_release (lock=0x80180d200) at /usr/src/lib/libthr/thread/thr_rtld.c:157
> 157 SAVE_ERRNO();
> (gdb)
> 160 state = l->lock.rw_state;
> (gdb)
> 161 if (_thr_rwlock_unlock(&l->lock) == 0) {
> (gdb)
> _thr_rwlock_unlock (rwlock=0x80180d200) at /usr/src/lib/libthr/thread/thr_umtx.h:249
> 249 state = rwlock->rw_state;
> (gdb)
> 250 if ((state & URWLOCK_WRITE_OWNER) != 0) {
> (gdb)
> 256 if (__predict_false(URWLOCK_READER_COUNT(state) == 0))
> (gdb)
> 260 URWLOCK_READER_COUNT(state) == 1)) {
> (gdb)
> 259 URWLOCK_READ_WAITERS)) != 0 &&
> (gdb)
> 262 state, state - 1))
> (gdb)
> 261 if (atomic_cmpset_rel_32(&rwlock->rw_state,
> (gdb)
> atomic_cmpset_int (dst=<optimized out>, expect=<optimized out>, src=0) at /usr/obj/usr/src/amd64.amd64/tmp/usr/include/machine/atomic.h:220
> 220 ATOMIC_CMPSET(int);
> (gdb)
> _thr_rwlock_unlock (rwlock=0x80180d200) at /usr/src/lib/libthr/thread/thr_umtx.h:261
> 261 if (atomic_cmpset_rel_32(&rwlock->rw_state,
> (gdb)
> _thr_rtld_lock_release (lock=<optimized out>) at /usr/src/lib/libthr/thread/thr_rtld.c:162
> 162 if ((state & URWLOCK_WRITE_OWNER) == 0)
> (gdb)
> 163 curthread->rdlock_count--;
> (gdb)
> 164 THR_CRITICAL_LEAVE(curthread);
> (gdb)
> _thr_ast (curthread=0x80864b000) at /usr/src/lib/libthr/thread/thr_sig.c:271
> 271 if (!THR_IN_CRITICAL(curthread)) {
> (gdb)
> 272 check_deferred_signal(curthread);
> (gdb)
> check_deferred_signal (curthread=0x80864b000) at /usr/src/lib/libthr/thread/thr_sig.c:332
> 332 if
> (__predict_true(curthread->deferred_siginfo.si_signo == 0 ||
> (gdb)
> 351 }
> (gdb)
> _thr_ast (curthread=0x80864b000) at /usr/src/lib/libthr/thread/thr_sig.c:273
> 273 check_suspend(curthread);
> (gdb)
> check_suspend (curthread=0x80864b000) at /usr/src/lib/libthr/thread/thr_sig.c:358
> 358 if (__predict_true((curthread->flags &
> (gdb)
> 401 }
> (gdb)
> _thr_ast (curthread=0x80864b000) at /usr/src/lib/libthr/thread/thr_sig.c:274
> 274 check_cancel(curthread, NULL);
> (gdb)
> check_cancel (curthread=0x80864b000, ucp=0x0) at /usr/src/lib/libthr/thread/thr_sig.c:283
> 283 if (__predict_true(!curthread->cancel_pending ||
> (gdb)
> _thr_ast (curthread=<optimized out>) at /usr/src/lib/libthr/thread/thr_sig.c:276
> 276 }
> (gdb)
> _thr_rtld_lock_release (lock=<optimized out>) at /usr/src/lib/libthr/thread/thr_rtld.c:166
> 166 RESTORE_ERRNO();
> (gdb)
> 167 }
> (gdb)
> setrlimit () at setrlimit.S:3
> 3 RSYSCALL(setrlimit)
> (gdb)
>
> Program received signal SIGSEGV, Segmentation fault.
> setrlimit () at setrlimit.S:3
> 3 RSYSCALL(setrlimit)
> (gdb)
>
> Program terminated with signal SIGSEGV, Segmentation fault.
> The program no longer exists.
> (gdb) q
>
> ====
>
> I'm sorry for the long post. Is there anything (else) I can do to
> further narrow it down?
>
> --
> Trond.
> _______________________________________________
> freebsd-stable@freebsd.org mailing list
> https://lists.freebsd.org/mailman/listinfo/freebsd-stable
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