From: Steven Rostedt <rostedt@goodmis.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: perf_fuzzer: BUG in kfree() in ftrace_graph_exit_task
Date: Mon, 31 Mar 2014 12:47:04 -0400 [thread overview]
Message-ID: <20140331124704.13c3cbcc@gandalf.local.home> (raw)
In-Reply-To: <alpine.DEB.2.02.1403311826280.14882@ionos.tec.linutronix.de>
On Mon, 31 Mar 2014 18:32:40 +0200 (CEST)
Thomas Gleixner <tglx@linutronix.de> wrote:
> On Mon, 31 Mar 2014, Vince Weaver wrote:
> >
> > This turned up with the perf_fuzzer, haswell, 3.14.
> >
> > I'm not sure if this is related to the other object corruption bug I am
> > seeing. The sympstoms are similar (BUG when dereferencing low invalid
> > kernel address) but this time the hrtimer code is not involved at all.
> >
> > This isn't reproducible, that is if I re-run the fuzzer with the same
> > random seed after reboot the bug doesn't trigger.
> >
> >
> > [ 5498.573458] BUG: unable to handle kernel NULL pointer dereference at 000000000000006c
> > [ 5498.585181] IP: [<ffffffff81189111>] kfree+0x91/0x220
> > [ 5498.593887] PGD 0
> > [ 5498.599365] Oops: 0000 [#1] SMP
> > [ 5498.606127] Dumping ftrace buffer:
> > [ 5498.612973] (ftrace buffer empty)
> > [ 5498.619868] Modules linked in: nfsd auth_rpcgss .....
> > [ 5498.720303] CPU: 1 PID: 13 Comm: ksoftirqd/1 Tainted: G W 3.14.0+ #14
>
> It's already tainted with W, so there was a warning before that
> crash. It would be interesting to see that as well.
>
Agreed, as the crash points to some pretty straight forward code. If
something happened to a task, it can corrupt the task ret_stack pointer
which would cause ftrace_graph_exit_task() to crash too.
-- Steve
next prev parent reply other threads:[~2014-03-31 16:47 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-31 16:23 Vince Weaver
2014-03-31 16:32 ` Thomas Gleixner
2014-03-31 16:47 ` Steven Rostedt [this message]
2014-03-31 17:04 ` Vince Weaver
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