From: Salvatore Bonaccorso <carnil@debian.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul Menzel <pmenzel@molgen.mpg.de>,
Jacob Pan <jacob.jun.pan@linux.intel.com>,
Len Brown <lenb@kernel.org>,
x86@kernel.org, LKML <linux-kernel@vger.kernel.org>,
linux-pm@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>,
Matthew Garrett <mjg59@google.com>
Subject: Re: [Linux 5.2.x] /sys/kernel/debug/tracing/events/power/cpu_idle/id: BUG: kernel NULL pointer dereference, address: 0000000000000000
Date: Sun, 11 Aug 2019 17:33:26 +0200 [thread overview]
Message-ID: <20190811153326.GA8036@eldamar.local> (raw)
In-Reply-To: <alpine.DEB.2.21.1908111456430.7324@nanos.tec.linutronix.de>
Thomas,
On Sun, Aug 11, 2019 at 02:58:15PM +0200, Thomas Gleixner wrote:
> Salvatore,
>
> On Sun, 11 Aug 2019, Salvatore Bonaccorso wrote:
> > On Sun, Aug 11, 2019 at 08:22:35AM +0200, Thomas Gleixner wrote:
> > > On Sat, 10 Aug 2019, Paul Menzel wrote:
> > > > For the record. It is also reproducible with Linux 5.2.6, and trying to print
> > > > the file contents with cat already fails.
> > > >
> > > > ```
> > > > $ sudo ls -l /sys/kernel/debug/tracing/events/power/cpu_idle/id
> > > > -r--r--r-- 1 root root 0 Aug 10 23:05
> > > > /sys/kernel/debug/tracing/events/power/cpu_idle/id
> > > > $ sudo cat /sys/kernel/debug/tracing/events/power/cpu_idle/id
> > > > Killed
> > > > ```
> >
> > This seems to be related to https://bugs.debian.org/934304 (in
> > particular https://bugs.debian.org/934304#29). The mentioned patch
> > features/all/lockdown/0031-tracefs-Restrict-tracefs-when-the-kernel-is-locked-d.patch
> > is a backport of https://patchwork.kernel.org/patch/11069661/ with
> > only change that it is converted back to the non-LSM lockdown API.
>
> So that's a debian kernel specific issue?
"yes". A kernel build without the above patch does not exhibit the
issue. So the issue is specific to that lockdown patch ("tracefs:
Restrict tracefs when the kernel is locked down").
Steven and Matthew are both CC'ed.
Regards,
Salvatore
next prev parent reply other threads:[~2019-08-11 15:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-10 16:33 [Linux 5.2.7] powertop --auto-tune: BUG: kernel NULL pointer dereference, address: 0000000000000000 Paul Menzel
2019-08-10 17:31 ` Thomas Gleixner
2019-08-10 18:28 ` Paul Menzel
2019-08-10 21:11 ` [Linux 5.2.x] /sys/kernel/debug/tracing/events/power/cpu_idle/id: " Paul Menzel
2019-08-11 6:22 ` Thomas Gleixner
2019-08-11 9:46 ` Salvatore Bonaccorso
2019-08-11 12:58 ` Thomas Gleixner
2019-08-11 15:33 ` Salvatore Bonaccorso [this message]
2019-08-12 15:28 ` Steven Rostedt
2019-08-12 16:24 ` Matthew Garrett
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