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Date:   Thu, 1 Oct 2020 16:06:53 -0700
From:   Andi Kleen <ak@linux.intel.com>
To:     Barry Song <song.bao.hua@hisilicon.com>
Cc:     linux-kernel@vger.kernel.org, linuxarm@huawei.com,
        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>,
        Namhyung Kim <namhyung@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Alexey Budankov <alexey.budankov@linux.intel.com>
Subject: Re: [PATCH] perf evlist: fix memory corruption for Kernel PMU event
Message-ID: <20201001230653.GM50079@tassilo.jf.intel.com>
References: <20201001115729.27116-1-song.bao.hua@hisilicon.com>
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On Fri, Oct 02, 2020 at 12:57:29AM +1300, Barry Song wrote:
> Commit 7736627b865d ("perf stat: Use affinity for closing file
> descriptors") will use FD(evsel, cpu, thread) to read and write
> file descriptors xyarray. For a kernel PMU event, this leads to
> serious memory corruption and perf crash.
> I have seen evlist->core.cpus->nr is 1 while evsel has cpus->nr
> with the total number of CPUs. so xyarray which is allocated by
> evlist->core.cpus->nr will get overflow. This leads to various
> segmentation faults in perf tool for kernel PMU events, eg:
> ./perf stat -e bus_cycles  sleep 1
> *** Error in `./perf': free(): invalid next size (fast): 0x00000000401e6370 ***
> Aborted (core dumped)

Thanks.

I believe there is already a patch queued for this.

The problem seems to only happen on ARM64.

-Andi