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

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Date:   Mon, 6 Mar 2017 13:17:42 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>
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>
Subject: Re: perf: use-after-free in perf_release

On Mon, Mar 6, 2017 at 1:13 PM, Peter Zijlstra <peterz@...radead.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.