[pulseaudio-discuss] PA 7.0 crash with KDE

[Takashi Iwai]

On Fri, 16 Oct 2015 13:50:58 +0200,
David Henningsson wrote:
> 
> 
> 
> On 2015-10-16 10:35, Takashi Iwai wrote:
> > On Fri, 16 Oct 2015 09:16:04 +0200,
> > David Henningsson wrote:
> >>
> >> (Adding pulseaudio-discuss to CC)
> >>
> >> On 2015-10-15 16:26, Takashi Iwai wrote:
> >>> Hi David,
> >>>
> >>> we got bug reports with PA 7.0 where the recent KDE crashes.
> >>> It seems that srbchannel=no works around it, so there is still
> >>> something fishy there.
> >>>
> >>> The bug report is found at
> >>>     http://bugzilla.opensuse.org/show_bug.cgi?id=950487
> >>
> >> Hi Takashi and thanks for reporting.
> >>
> >> I've tried running PA 7.0's pactl under valgrind, and it reports no
> >> errors here. Still, looking at the one of the backtraces the value of f
> >> is something interesting:
> >>
> >> #6  flush (f=f at entry=0x4545454545454545) at pulsecore/fdsem.c:143
> >> #7  0x00007fe30f378fc2 in pa_fdsem_before_poll (f=0x4545454545454545) at
> >> pulsecore/fdsem.c:295
> >> #8  0x00007fe30f38f697 in srbchannel_rwloop (sr=0x25bdd40) at
> >> pulsecore/srbchannel.c:203
> >>
> >> Does 0x4545454545454545 mean anything specific on OpenSUSE? (Like, a
> >> magic clear value or something?)
> >
> > I don't think it's openSUSE specific.  It's likely the guard put by
> > either gcc or glibc.
> > FWIW, we pass the default optimization flags like:
> >    CFLAGS=-fmessage-length=0 -grecord-gcc-switches -O2 -Wall \
> >      -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables \
> >      -fasynchronous-unwind-tables -g -fPIE
> >
> > The problem was reported from both gcc-4.8 and gcc-5.x systems, so the
> > gcc version is likely irrelevant.
> >
> >> Also, are there any distro patches to OpenSUSE and if so, where can I
> >> find them?
> >
> > No, there is no patches apparently relevant with this.  Actually there are
> > three patches, one is to check an additional environment check in
> > start-pulseaudio-x11, another is to suppress an error log at
> > sockaddr_prepare(), and the last is a fix in memset() size in
> > echo-cancel/adrian-aec.c.  But all these should be safe.
> >
> > All sources, patches, build log and binaries are found in OBS, e.g. at
> >    https://build.opensuse.org/package/show/multimedia:libs/pulseaudio
> 
> Ok, thanks.
> 
> I've been trying to analyze the backtrace.
> 
> My guess is that the srbchannel is being destroyed somehow, but I don't 
> see how. Any chance we can get more info from this, e g, build 
> pulseaudio's client library with -DDEBUG_SRBCHANNEL=1 and then get a log 
> like this:
> 
> PULSE_LOG=99 pactl info
> 
> ...which includes the crash?

OK, I'm building a package with the debug enabled and will ask
reporters to test with it.

> Also, if the srbchannel gets destroyed and replaced by another 
> srbchannel (eh?), it's possible that the below would help:
> 
> diff --git a/src/pulsecore/pstream.c b/src/pulsecore/pstream.c
> index 8c14fbb..06063bb 100644
> --- a/src/pulsecore/pstream.c
> +++ b/src/pulsecore/pstream.c
> @@ -223,7 +223,7 @@ static bool srb_callback(pa_srbchannel *srb, void 
> *userdata) {
>       pa_assert(p->srb == srb);
> 
>       do_pstream_read_write(p);
> -    return p->srb != NULL;
> +    return p->srb == srb;
>   }
> 
> 
> ...but that's an even wilder guess, at this point.

But such a condition should have been caught by pa_assert(), no?


Takashi