From: Dmitry Vyukov <dvyukov@google.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
syzkaller <syzkaller@googlegroups.com>,
Kostya Serebryany <kcc@google.com>,
Alexander Potapenko <glider@google.com>,
Eric Dumazet <edumazet@google.com>,
Sasha Levin <sasha.levin@oracle.com>
Subject: Re: use-after-free in __perf_install_in_context
Date: Fri, 4 Dec 2015 22:00:21 +0100 [thread overview]
Message-ID: <CACT4Y+a6O=5C_hMWC3FHw76n8WkmN+_-MSxwcDcLwHz46vZnNA@mail.gmail.com> (raw)
In-Reply-To: <20151204203212.GA64517@ast-mbp.thefacebook.com>
On Fri, Dec 4, 2015 at 9:32 PM, Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
> On Fri, Dec 04, 2015 at 09:04:35PM +0100, Dmitry Vyukov wrote:
>> Hello,
>>
>> While running syzkaller fuzzer I am seeing lots of the following
>> use-after-free reports. Unfortunately all my numerous attempts to
>> reproduce them in a controlled environment failed. They pop up during
>> fuzzing periodically (once in several hours in a single VM), but
>> whenever I try to stress-replay what happened in the VM before the
>> report, the use-after-free does not reproduce. Can somebody
>> knowledgeable in perf subsystem look at the report? Maybe it is
>> possible to figure out what happened based purely on the report. I can
>> pretty reliably test any proposed fixes.
>> All reports look like this one. Then it is usually followed by other
>> reports and eventually kernel hangs or dies. What happens in the
>> fuzzer is essentially random syscalls with random arguments, tasks
>> born and die concurrently and so on. I was able to reproduce it by
>> restricting syscalls only to perf_event_open, perf ioctls and bpf
>> syscall.
>
> For the sake of trying to narrow it down:
> does the error disappear when you stop using bpf syscall in your fuzzing?
> If yes, then I could have missed some interaction between perf_event_free,
> kprobe free and bpf_prog_free.
> There was a race there before.
> May be there is still something else.
It is a good question. I will test it.
next prev parent reply other threads:[~2015-12-04 21:00 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-04 20:04 use-after-free in __perf_install_in_context Dmitry Vyukov
2015-12-04 20:32 ` Alexei Starovoitov
2015-12-04 21:00 ` Dmitry Vyukov [this message]
2015-12-07 11:04 ` Dmitry Vyukov
2015-12-07 11:06 ` Dmitry Vyukov
2015-12-07 11:24 ` Dmitry Vyukov
2015-12-07 15:36 ` Peter Zijlstra
2015-12-07 16:09 ` Dmitry Vyukov
2015-12-08 3:24 ` Alexei Starovoitov
2015-12-08 16:12 ` Dmitry Vyukov
2015-12-08 17:54 ` Alexei Starovoitov
2015-12-08 17:56 ` Dmitry Vyukov
2015-12-08 18:05 ` Alexei Starovoitov
2015-12-08 18:35 ` Dmitry Vyukov
2015-12-08 19:56 ` Alexei Starovoitov
2015-12-09 9:17 ` Dmitry Vyukov
2015-12-10 3:54 ` Alexei Starovoitov
2015-12-10 9:02 ` Peter Zijlstra
2015-12-10 17:03 ` Alexei Starovoitov
2015-12-11 8:14 ` Ingo Molnar
2015-12-15 13:11 ` Dmitry Vyukov
2015-12-08 16:44 ` Peter Zijlstra
2015-12-08 19:14 ` Dmitry Vyukov
2015-12-10 19:57 ` Peter Zijlstra
2015-12-15 13:09 ` Dmitry Vyukov
2015-12-17 14:06 ` Peter Zijlstra
2015-12-17 14:08 ` Dmitry Vyukov
2015-12-17 14:26 ` Peter Zijlstra
2015-12-17 14:28 ` Peter Zijlstra
2015-12-17 14:35 ` Dmitry Vyukov
2015-12-17 14:43 ` Peter Zijlstra
2015-12-31 17:15 ` Dmitry Vyukov
2016-01-05 12:17 ` Peter Zijlstra
2016-01-08 8:40 ` Dmitry Vyukov
2016-01-08 10:28 ` Dmitry Vyukov
2016-01-06 18:46 ` [tip:perf/core] perf: Fix race in perf_event_exec() tip-bot for Peter Zijlstra
2016-01-06 18:56 ` Eric Dumazet
2016-01-07 13:40 ` Peter Zijlstra
2016-01-07 16:26 ` Paul E. McKenney
2016-01-07 16:36 ` Eric Dumazet
2016-01-07 16:46 ` Paul E. McKenney
2015-12-08 16:22 ` use-after-free in __perf_install_in_context Peter Zijlstra
2015-12-08 18:57 ` Ingo Molnar
2015-12-09 9:05 ` Peter Zijlstra
2015-12-08 16:27 ` Peter Zijlstra
2015-12-08 16:50 ` Dmitry Vyukov
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