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From: Dave Jones <davej@redhat.com>
To: David Ahern <dsahern@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	paulmck@linux.vnet.ibm.com,
	Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: suspicious RCU usage (perf)
Date: Mon, 26 Aug 2013 15:49:24 -0400	[thread overview]
Message-ID: <20130826194923.GA1549@redhat.com> (raw)
In-Reply-To: <521BAFD3.2060404@gmail.com>

On Mon, Aug 26, 2013 at 01:43:15PM -0600, David Ahern wrote:
 > On 8/26/13 12:29 PM, Dave Jones wrote:
 > > On Mon, Aug 26, 2013 at 02:18:14PM -0400, Steven Rostedt wrote:
 > >   > On Mon, 26 Aug 2013 13:50:12 -0400
 > >   > Dave Jones <davej@redhat.com> wrote:
 > >   > >
 > >   > > This was triggered as a regular user fwiw.
 > >   > > I had not been running perf, or any other tracing. It was just left
 > >   > > fuzzing over the weekend with no interaction at all.
 > >   >
 > >   > So you are telling me that ftrace was enabled by a regular user? If so,
 > >   > that's a huge issue.
 > >
 > > quite.
 > >
 > >   > So my question to you. If you were not running perf or any other
 > >   > tracing, and this is all just non-root user. How the hell did perf
 > >   > function tracing get started on your box????
 > >
 > > What mechanisms are available that would trigger it being enabled ?
 > >
 > > Is there some path through sys_perf_open_event that might be
 > > missing a capability check perhaps ?
 > 
 > Do you have /sys/kernel/debug with access permissions?

Ah, yeah, that'll be it. Good catch.

Sorry for the false alarm Steve ;)

	Dave


  reply	other threads:[~2013-08-26 19:49 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-26 14:58 suspicious RCU usage (perf) Dave Jones
2013-08-26 16:29 ` Paul E. McKenney
2013-08-26 17:30   ` Steven Rostedt
2013-08-26 17:50     ` Dave Jones
2013-08-26 18:18       ` Steven Rostedt
2013-08-26 18:29         ` Dave Jones
2013-08-26 19:03           ` Steven Rostedt
2013-08-27 12:16             ` Peter Zijlstra
2013-08-30 15:49               ` Frederic Weisbecker
2013-08-30 15:52               ` Frederic Weisbecker
2013-08-30 15:59                 ` Peter Zijlstra
2013-08-30 16:06                   ` Frederic Weisbecker
2013-08-26 19:43           ` David Ahern
2013-08-26 19:49             ` Dave Jones [this message]
2013-08-27 13:10               ` Steven Rostedt
2013-08-27 13:58                 ` David Ahern
2013-08-27 14:13                   ` Dave Jones

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