From: Song Liu <liu.song.a23@gmail.com>
To: Jiri Olsa <jolsa@redhat.com>
Cc: open list <linux-kernel@vger.kernel.org>,
Jiri Olsa <jolsa@kernel.org>,
acme@kernel.org
Subject: Re: perf segfault in in ordered_events__free()
Date: Wed, 16 Jan 2019 23:33:55 -0800 [thread overview]
Message-ID: <CAPhsuW7AktPKcw6KG7kRm-5Jm_TnhdPczT_G8fP3c49jT0DqWQ@mail.gmail.com> (raw)
In-Reply-To: <CAPhsuW6g9FOXvWA=9_Ab7Qo2B=DHraTPCT_ekmywF8soZz90=A@mail.gmail.com>
On Wed, Jan 16, 2019 at 1:53 PM Song Liu <liu.song.a23@gmail.com> wrote:
>
> Thanks Jiri!
>
> On Wed, Jan 16, 2019 at 1:34 PM Jiri Olsa <jolsa@redhat.com> wrote:
> >
> > On Wed, Jan 16, 2019 at 10:57:49AM -0800, Song Liu wrote:
> > > Hi,
> > >
> > > We are debugging a segfault of perf in ordered_events__free().
> >
> > hi,
> > any backtrace or info on how to reproduce it?
>
> Here is the backtrace:
>
> #0 0x0000000000500055 in ordered_events(float, long double,...)(...) ()
> #1 0x0000000000500196 in ordered_events.reinit ()
> #2 0x00000000004fe413 in perf_session.process_events ()
> #3 0x0000000000440431 in cmd_record ()
> #4 0x00000000004a439f in run_builtin ()
> #5 0x000000000042b3e5 in main ()"
>
> >
> > > Disassemble shows the segfault was caused by oe->buff == NULL
> > > in the following line:
> > >
> > > /*
> > > * Current buffer might not have all the events allocated
> > > * yet, we need to free only allocated ones ...
> > > */
> > > list_del(&oe->buffer->list);
> > >
> > > After poking around the code, I suspect it is caused by the following
> > > condition in alloc_event():
> > >
> > > } else if (oe->buffer) {
> > > new = &oe->buffer->event[oe->buffer_idx];
> > > if (++oe->buffer_idx == MAX_SAMPLE_BUFFER)
> > > oe->buffer = NULL;
> >
> >
> > argh.. yea, we need to check oe->buffer in ordered_events__free
> >
> > would attached change fix it for you?
>
> Let me try roll a fixed version to confirm.
Yes, the patch fixes this segfault. Please CC me on the official patch to
back port the official version.
Thanks,
Song
next prev parent reply other threads:[~2019-01-17 7:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-16 18:57 perf segfault in in ordered_events__free() Song Liu
2019-01-16 21:34 ` Jiri Olsa
2019-01-16 21:53 ` Song Liu
2019-01-17 7:33 ` Song Liu [this message]
2019-01-17 9:18 ` Jiri Olsa
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