lldb unusable for regular user

[Vladimir Zakharov]

Hello!

lldb coredumps for regular user, but works for root.

> uname -a
FreeBSD vzakharov 12.0-CURRENT FreeBSD 12.0-CURRENT #0 r323675: Sun Sep 17 21:14:33 MSK 2017     root at vzakharov:/home/obj/usr/src/sys/GENERIC-NODEBUG  amd64
> cat test.c
#include <stdio.h>
#include <unistd.h>

int main()
{
  printf("PID: %d\n", getpid());
  sleep(10);
  return 0;
}
> cc -O0 -g test.c -o test
> lldb ./test
(lldb) target create "./test"
Current executable set to './test' (x86_64).
(lldb) run
Process 37758 launching
Process 37758 launched: './test' (x86_64)
Segmentation fault (core dumped)
Exit 139
> sudo lldb ./test
(lldb) target create "./test"
Current executable set to './test' (x86_64).
(lldb) run
Process 37776 launching
Process 37776 launched: './test' (x86_64)
PID: 37776
Process 37776 exited with status = 0 (0x00000000)
(lldb)


Postmortem by gdb:
> gdb ./test test.core
...
[New LWP 101456]
Core was generated by `./test'.
Program terminated with signal SIGTRAP, Trace/breakpoint trap.
#0  _start (ap=0x7fffffffe858, cleanup=0x800605910 <rtld_exit>) at /usr/src/lib/csu/amd64/crt1.c:50
50      {
(gdb) bt
#0  _start (ap=0x7fffffffe858, cleanup=0x800605910 <rtld_exit>) at /usr/src/lib/csu/amd64/crt1.c:50
(gdb) f
#0  _start (ap=0x7fffffffe858, cleanup=0x800605910 <rtld_exit>) at /usr/src/lib/csu/amd64/crt1.c:50
50      {

> gdb `which lldb` lldb.core
...
Reading symbols from /usr/bin/lldb...Reading symbols from /usr/lib/debug//usr/bin/lldb.debug...done.
done.
[New LWP 101610]
[New LWP 100968]
[New LWP 100126]
[New LWP 101631]
[New LWP 101637]
[New LWP 101662]
[New LWP 101672]
[New LWP 100337]
[New LWP 101593]
Core was generated by `lldb ./test'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  x86_64_freebsd_fallback_frame_state (context=0x7fffddff6e20, context=0x7fffddff6e20, fs=0x7fffddff6b70) at ./md-unwind-support.h:60
60      ./md-unwind-support.h: No such file or directory.
[Current thread is 1 (LWP 101610)]
(gdb) f
#0  x86_64_freebsd_fallback_frame_state (context=0x7fffddff6e20, context=0x7fffddff6e20, fs=0x7fffddff6b70) at ./md-unwind-support.h:60
60      in ./md-unwind-support.h
(gdb) bt
#0  x86_64_freebsd_fallback_frame_state (context=0x7fffddff6e20, context=0x7fffddff6e20, fs=0x7fffddff6b70) at ./md-unwind-support.h:60
#1  uw_frame_state_for (context=context at entry=0x7fffddff6e20, fs=fs at entry=0x7fffddff6b70) at /wrkdirs/usr/ports/lang/gcc6/work/gcc-6.4.0/libgcc/unwind-dw2.c:1249
#2  0x0000000804f6cffb in _Unwind_ForcedUnwind_Phase2 (exc=exc at entry=0x806b23230, context=context at entry=0x7fffddff6e20) at /wrkdirs/usr/ports/lang/gcc6/work/gcc-6.4.0/libgcc/unwind.inc:155
#3  0x0000000804f6d334 in _Unwind_ForcedUnwind (exc=0x806b23230, stop=0x804631760 <thread_unwind_stop>, stop_argument=<optimized out>) at /wrkdirs/usr/ports/lang/gcc6/work/gcc-6.4.0/libgcc/unwind.inc:207
#4  0x00000008046315c3 in _Unwind_ForcedUnwind (ex=<optimized out>, stop_func=0xe, stop_arg=0x806b23000) at /usr/src/lib/libthr/thread/thr_exit.c:106
#5  thread_unwind () at /usr/src/lib/libthr/thread/thr_exit.c:172
#6  _pthread_exit_mask (status=<optimized out>, mask=<optimized out>) at /usr/src/lib/libthr/thread/thr_exit.c:254
#7  0x00000008046313eb in _pthread_exit (status=0x806b23000) at /usr/src/lib/libthr/thread/thr_exit.c:206
#8  0x0000000804623c0d in thread_start (curthread=0x806b23000) at /usr/src/lib/libthr/thread/thr_create.c:289
#9  0x00007fffdddf7000 in ?? ()
Backtrace stopped: Cannot access memory at address 0x7fffddff7000

-- 
Regards,                 | "In theory there is no difference between theory
  Vladimir Zakharov      | and practice. In practice there is."- Yogi Berra