linux-kernel - Re: perf: use-after-free in perf

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Message-ID: <20170307093759.GU6500@twins.programming.kicks-ass.net>
Date:   Tue, 7 Mar 2017 10:37:59 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        syzkaller <syzkaller@...glegroups.com>,
        Oleg Nesterov <oleg@...hat.com>
Subject: Re: perf: use-after-free in perf_release

On Tue, Mar 07, 2017 at 10:26:20AM +0100, Dmitry Vyukov wrote:
> On Tue, Mar 7, 2017 at 10:08 AM, Peter Zijlstra <peterz@...radead.org> wrote:
> > On Mon, Mar 06, 2017 at 02:34:50PM +0100, Dmitry Vyukov wrote:
> >> FWIW here are 2 syzkaller programs that triggered the bug:
> >> https://gist.githubusercontent.com/dvyukov/d67f980050589775237a7fbdff226bec/raw/4bca72861cb2ede64059b6dad403e19f425a361f/gistfile1.txt
> >
> > Hurm, previously your gistfile thingies were actual C, but this thing is
> > gibberish. How do I run it?
> 
> The same way we did it here:
> https://groups.google.com/d/msg/syzkaller/MHXa-o8foyc/yrGfDOrwAQAJ

Oh right, completely forgot about that. The last gistfile stuff I found
in my history were actual C files.

> This will run it in infinite loop in 10 parallel processes:
> ./syz-execprog -repeat=0 -procs=10 -sandbox=namespace gistfile1.txt
> -sandbox=namespace will require CONFIG_USER_NS=y, I am not sure if it
> is actually required, but that's how bots triggered it. You can do
> -sandbox=none as well.

I still have an ancient syzcaller; -sandbox doesn't exist and I needed
to add -executor=bin/syz-executor but now it appears to run.

I'll go up procs, 10 is somewhat low I feel.


---

root@...-ep:~/gopath/src/github.com/google/syzkaller# ./bin/syz-execprog -repeat=0 -procs=10 -executor=bin/syz-executor gistfile2.txt
2017/03/07 10:35:14 parsed 2 programs
2017/03/07 10:35:14 executed 0 programs
result: failed=false hanged=false err=executor is not serving

2017/03/07 10:36:14 executed 10 programs
result: failed=false hanged=false err=executor is not serving

result: failed=false hanged=false err=executor is not serving

result: failed=false hanged=false err=executor is not serving

result: failed=false hanged=false err=executor is not serving

result: failed=false hanged=false err=executor is not serving

result: failed=false hanged=false err=executor is not serving

result: failed=false hanged=false err=executor is not serving

result: failed=false hanged=false err=executor is not serving

result: failed=false hanged=false err=executor is not serving