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    Subject[PATCH 5.8 401/633] perf stat: Fix out of bounds CPU map access when handling armv8_pmu events
    Date
    From: Namhyung Kim <namhyung@kernel.org>

    [ Upstream commit bef69bd7cfc363ab94b84ea29102f3e913ed3c6c ]

    It was reported that 'perf stat' crashed when using with armv8_pmu (CPU)
    events with the task mode. As 'perf stat' uses an empty cpu map for
    task mode but armv8_pmu has its own cpu mask, it has confused which map
    it should use when accessing file descriptors and this causes segfaults:

    (gdb) bt
    #0 0x0000000000603fc8 in perf_evsel__close_fd_cpu (evsel=<optimized out>,
    cpu=<optimized out>) at evsel.c:122
    #1 perf_evsel__close_cpu (evsel=evsel@entry=0x716e950, cpu=7) at evsel.c:156
    #2 0x00000000004d4718 in evlist__close (evlist=0x70a7cb0) at util/evlist.c:1242
    #3 0x0000000000453404 in __run_perf_stat (argc=3, argc@entry=1, argv=0x30,
    argv@entry=0xfffffaea2f90, run_idx=119, run_idx@entry=1701998435)
    at builtin-stat.c:929
    #4 0x0000000000455058 in run_perf_stat (run_idx=1701998435, argv=0xfffffaea2f90,
    argc=1) at builtin-stat.c:947
    #5 cmd_stat (argc=1, argv=0xfffffaea2f90) at builtin-stat.c:2357
    #6 0x00000000004bb888 in run_builtin (p=p@entry=0x9764b8 <commands+288>,
    argc=argc@entry=4, argv=argv@entry=0xfffffaea2f90) at perf.c:312
    #7 0x00000000004bbb54 in handle_internal_command (argc=argc@entry=4,
    argv=argv@entry=0xfffffaea2f90) at perf.c:364
    #8 0x0000000000435378 in run_argv (argcp=<synthetic pointer>,
    argv=<synthetic pointer>) at perf.c:408
    #9 main (argc=4, argv=0xfffffaea2f90) at perf.c:538

    To fix this, I simply used the given cpu map unless the evsel actually
    is not a system-wide event (like uncore events).

    Fixes: 7736627b865d ("perf stat: Use affinity for closing file descriptors")
    Reported-by: Wei Li <liwei391@huawei.com>
    Signed-off-by: Namhyung Kim <namhyung@kernel.org>
    Tested-by: Barry Song <song.bao.hua@hisilicon.com>
    Acked-by: Jiri Olsa <jolsa@redhat.com>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Stephane Eranian <eranian@google.com>
    Link: http://lore.kernel.org/lkml/20201007081311.1831003-1-namhyung@kernel.org
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    tools/lib/perf/evlist.c | 3 +++
    1 file changed, 3 insertions(+)

    diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
    index 6a875a0f01bb0..233592c5a52c7 100644
    --- a/tools/lib/perf/evlist.c
    +++ b/tools/lib/perf/evlist.c
    @@ -45,6 +45,9 @@ static void __perf_evlist__propagate_maps(struct perf_evlist *evlist,
    if (!evsel->own_cpus || evlist->has_user_cpus) {
    perf_cpu_map__put(evsel->cpus);
    evsel->cpus = perf_cpu_map__get(evlist->cpus);
    + } else if (!evsel->system_wide && perf_cpu_map__empty(evlist->cpus)) {
    + perf_cpu_map__put(evsel->cpus);
    + evsel->cpus = perf_cpu_map__get(evlist->cpus);
    } else if (evsel->cpus != evsel->own_cpus) {
    perf_cpu_map__put(evsel->cpus);
    evsel->cpus = perf_cpu_map__get(evsel->own_cpus);
    --
    2.25.1


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