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Date: Mon, 6 Mar 2017 13:23:27 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        syzkaller <syzkaller@googlegroups.com>
Subject: Re: perf: use-after-free in perf_release
Message-ID: <20170306122327.GJ6500@twins.programming.kicks-ass.net>
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On Mon, Mar 06, 2017 at 01:17:42PM +0100, Dmitry Vyukov wrote:
> On Mon, Mar 6, 2017 at 1:13 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> > On Mon, Mar 06, 2017 at 10:57:07AM +0100, Dmitry Vyukov wrote:
> >> Hello,
> >>
> >> I've got the following use-after-free report while running syzkaller
> >> fuzzer on 86292b33d4b79ee03e2f43ea0381ef85f077c760. Note that the task
> >> is freed right in copy_process due to some error, but it's referenced
> >> by another thread in perf subsystem.
> >
> > Weird... you don't happen to have a reproduction case available?
> 
> 
> Unfortunately no. I've looked at both logs that I have and there are
> no memory allocation failures preceding the crash (however maybe
> somebody used NOWARN?). But probably if you inject an error into
> copy_process somewhere after perf_event_init_task, it should reproduce
> the bug with KASAN I think.

I'll try. Thanks!