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From:   Namhyung Kim <namhyung@kernel.org>
Date:   Fri, 19 Jun 2020 22:12:56 +0900
Message-ID: <CAM9d7cgX4v+sBnpd3r1h+MO-U5mNYsAg7JN_O56h=sjjZPhy9g@mail.gmail.com>
Subject: Re: [PATCH] [perf] Fix null pointer deference in nest_epollfd
To:     gaurav singh <gaurav1086@gmail.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Tommi Rantala <tommi.t.rantala@nokia.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "open list:PERFORMANCE EVENTS SUBSYSTEM" 
        <linux-kernel@vger.kernel.org>
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On Fri, Jun 19, 2020 at 6:28 AM gaurav singh <gaurav1086@gmail.com> wrote:
>
> multiqu is a static bool which is never assigned and nested is a static int (=0)

It's set by command line option (-m).

Thanks
Namhyung


> and only assigned in nest_epollfd(). Hence,
>
>         if (nested)
>             nest_epollfd(NULL);
>
> probably never gets executed.