#1228 segfault whith jack in libthread_db

[kubriel]

gdb pd
GNU gdb (GDB) 7.10
.............
Type "apropos word" to search for commands related to "word"...
Reading symbols from pd...(no debugging symbols found)...done.
(gdb) run -jack
Starting program: /usr/local/bin/pd -jack
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".

Program received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x00000000004b9e5e in jack_open_audio ()
#2  0x000000000046b29e in sys_reopen_audio ()
#3  0x0000000000462591 in sys_main ()
#4  0x00007ffff6c2f610 in __libc_start_main () from /usr/lib/libc.so.6
#5  0x0000000000411bc9 in _start ()
(gdb) watchdog: signaling pd...
kill
Kill the program being debugged? (y or n) y
watchdog: signaling pd...

i cannot reproduce it anywhere else, but i dont know where can be the problem in this not very fresh arch linux installation(it worked before).
pd from git, but its same with pd from repo.
kernel 4.2.5-1-ARCH

just to let you know..

[IOhannes m zmölnig]

so it crashes on startup, without you doing anything? (in the gdb-session we only see that you start Pd and that it then crashes; n oclue what you are doing in Pd)

do other jack-based applications work?

[IOhannes m zmölnig]

also: is jackd running? (and which version of jackd are you using?)

[Anonymous]

i did nothing, pd window was not even opened.
jackd is running. it is 1.9.10-3. other applications running fine.

[Anonymous]

I can confirm that. I'm also on archlinux:

kernel: linux-rt 4.1.13-rt15-1-rt
Pd-0.46.7
jackdmp 1.9.10

2016-01-24 12:27 GMT+01:00 kubriel kubriel@users.sf.net:

---

• [bugs:#1228] http://sourceforge.net/p/pure-data/bugs/1228/ segfault
  whith jack in libthread_db*

Status: open
Group: v0.46
Labels: segfault jack
Created: Sun Jan 24, 2016 11:27 AM UTC by kubriel
Last Updated: Sun Jan 24, 2016 11:27 AM UTC
Owner: nobody

gdb pd
GNU gdb (GDB) 7.10
.............
Type "apropos word" to search for commands related to "word"...
Reading symbols from pd...(no debugging symbols found)...done.
(gdb) run -jack
Starting program: /usr/local/bin/pd -jack
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".

Program received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
(gdb) bt
0 0x0000000000000000 in ?? () 1 0x00000000004b9e5e in jack_open_audio () 2
0x000000000046b29e in sys_reopen_audio () 3 0x0000000000462591 in
sys_main () 4 0x00007ffff6c2f610 in __libc_start_main () from
/usr/lib/libc.so.6 5 0x0000000000411bc9 in _start ()

(gdb) watchdog: signaling pd...
kill
Kill the program being debugged? (y or n) y
watchdog: signaling pd...

i cannot reproduce it anywhere else, but i dont know where can be the
problem in this not very fresh arch linux installation(it worked before).
pd from git, but its same with pd from repo.
kernel 4.2.5-1-ARCH

just to let you know..

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[Xavier Miller]

Hi!

Same problem here. pd-0.46-7 segfaults with jack-1.9.10 on Gentoo Linux (x86_64).
I tried with jackd and jack-dbus.

If I disable jack from the configure script, I can run pd with ALSA.
jack applications are OK.

[Xavier Miller]

PD 0.45 is OK. I see that null buffer tests are added in src/s_audio_jack.c. Maybe there is one missing test or bracket there (see my diff).

[Anonymous]

There's a suggested fix in the Arch Linux bug report here:
https://bugs.archlinux.org/task/45006

This suggests, that something is wrong with the CFLAGS/CPPFLAGS

[IOhannes m zmölnig]

to me this looks like the arch-recipe for building Pd is broken (rather than a problem with Pd itself).

in any case, it would be useful to know what those build-flags hacks actually change (all instructions linked to from the arch-fix only involve tweaking the arch-buildprocess;).

i suspect that arch by default enables some hardening flags during compilation, and the maintainers of the arch packages for Pd haven't disabled this.

[Anonymous]

The suggested fix for Arch Linux introduces other weird behavior with pd. It makes it "unclosable" with a "messaging watchdog" notification upon trying to close pd, which then never happens.
The JACK connection works fine though...

[IOhannes m zmölnig]

so what is the difference that the suggested fix introduces?

[Anonymous]

The suggested fix is to ignore the global makeflags and buildflags and use pd's provided ones. This means: With the standard global Arch Linux ones the support for JACK breaks. With the pd provided make-/buildflags JACK support works, but the "won't close" bug is introduced (more on that below).

Arch Linux's current flags for makepkg (the build system) are:
CFLAGS="-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong"
CPPFLAGS="-D_FORTIFY_SOURCE=2"

Currently pd is build as follows:
https://paste.sleepmap.de/view/1c1d393b

The fix (introducing the "won't close" bug would look as follows:
https://paste.sleepmap.de/view/491612a2
(changes are in the options array)

Side note on the "won't close" bug:
It seems to be related to JACK, too, or to the .pdsettings file for that matter.
I deleted the old .pdsettings and restarted pd, reconnected with JACK, saved those settings and suddenly pd has no troubles closing.
Otherwise verbose messages showed an endless iteration of "watchdog: signaling pd", but nothing happens and pd just hangs.
Not sure what to make of it yet, but will open a bug report for it, if I encounter it again.

[IOhannes m zmölnig]

i'm still slightly mystified by the build-flags problem: on Debian we use

CFLAGS="-g -O2 -fstack-protector-strong -Wformat -Werror=format-security" LDFLAGS="-Wl,-z,relro -Wl,--as-needed"

which seems reasonable similar (I suspect that the problem really comes from any hardening flags , and is unrelated to CPU-optimization).
having said that, i wonder why the Debian builds have omitted the CPPFLAGS="-D_FORTIFY_SOURCE=2"

[IOhannes m zmölnig]

thanks for the detailed explanation.

the won't close bug should only appear if Pd started jackd (rather than connecting to an already running jackd), and is fixed with Pd-0.7 (and Pd-0.46-7). (The fix is merely to not autostart jackd at all)

[IOhannes m zmölnig]

for the record: the won't close bug has been
- reported as [#697] and [#909]
- and has been fixed as ab33f9b2 (resp. 62906ddf in the 0.46 branch)

... so there is little value in reporting it again...

[Anonymous]

Hmm, I actually never autostart JACK but use a separate systemd user unit for it instead to get around dbus ;-)
In any case, it seems to work currently, but I have experienced the issue on 46-7.

I hope, that the PKGBUILD will be fixed downstream with proper buildflags eventually...

[IOhannes m zmölnig]

please check whether https://github.com/pure-data/pure-data/pull/93 fixes the issue for you.

[kubriel]

cannot check it, as i dont use arch now.
i never met this on debian.

thanks

k

On 07/07/17 00:38, "IOhannes m zmölnig" wrote:

please check whether https://github.com/pure-data/pure-data/pull/93
fixes the issue for you.

---

[bugs:#1228] https://sourceforge.net/p/pure-data/bugs/1228/
segfault whith jack in libthread_db

Status: pending-works-for-me
Group: v0.46
Labels: puredata jack crash segfault
Created: Sun Jan 24, 2016 11:27 AM UTC by kubriel
Last Updated: Fri May 27, 2016 12:45 AM UTC
Owner: nobody

gdb pd
GNU gdb (GDB) 7.10
.............
Type "apropos word" to search for commands related to "word"...
Reading symbols from pd...(no debugging symbols found)...done.
(gdb) run -jack
Starting program: /usr/local/bin/pd -jack
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".

Program received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
(gdb) bt

0 0x0000000000000000 in ?? ()

1 0x00000000004b9e5e in jack_open_audio ()

2 0x000000000046b29e in sys_reopen_audio ()

3 0x0000000000462591 in sys_main ()

4 0x00007ffff6c2f610 in __libc_start_main () from /usr/lib/libc.so.6

5 0x0000000000411bc9 in _start ()

(gdb) watchdog: signaling pd...
kill
Kill the program being debugged? (y or n) y
watchdog: signaling pd...

i cannot reproduce it anywhere else, but i dont know where can be the
problem in this not very fresh arch linux installation(it worked before).
pd from git, but its same with pd from repo.
kernel 4.2.5-1-ARCH

just to let you know..

---

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