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    Subject[PATCH 5.4 021/151] perf trace: Fix segfault when trying to trace events by cgroup
    Date
    From: Stanislav Ivanichkin <sivanichkin@yandex-team.ru>

    [ Upstream commit a6293f36ac92ab513771a98efe486477be2f981f ]

    # ./perf trace -e sched:sched_switch -G test -a sleep 1
    perf: Segmentation fault
    Obtained 11 stack frames.
    ./perf(sighandler_dump_stack+0x43) [0x55cfdc636db3]
    /lib/x86_64-linux-gnu/libc.so.6(+0x3efcf) [0x7fd23eecafcf]
    ./perf(parse_cgroups+0x36) [0x55cfdc673f36]
    ./perf(+0x3186ed) [0x55cfdc70d6ed]
    ./perf(parse_options_subcommand+0x629) [0x55cfdc70e999]
    ./perf(cmd_trace+0x9c2) [0x55cfdc5ad6d2]
    ./perf(+0x1e8ae0) [0x55cfdc5ddae0]
    ./perf(+0x1e8ded) [0x55cfdc5ddded]
    ./perf(main+0x370) [0x55cfdc556f00]
    /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe6) [0x7fd23eeadb96]
    ./perf(_start+0x29) [0x55cfdc557389]
    Segmentation fault
    #

    It happens because "struct trace" in option->value is passed to the
    parse_cgroups function instead of "struct evlist".

    Fixes: 9ea42ba4411ac ("perf trace: Support setting cgroups as targets")
    Signed-off-by: Stanislav Ivanichkin <sivanichkin@yandex-team.ru>
    Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Acked-by: Namhyung Kim <namhyung@kernel.org>
    Cc: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
    Link: http://lore.kernel.org/lkml/20201027094357.94881-1-sivanichkin@yandex-team.ru
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    tools/perf/builtin-trace.c | 15 +++++++++------
    1 file changed, 9 insertions(+), 6 deletions(-)

    diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
    index bb5130d021554..a5201de1a191d 100644
    --- a/tools/perf/builtin-trace.c
    +++ b/tools/perf/builtin-trace.c
    @@ -3979,9 +3979,9 @@ do_concat:
    err = 0;

    if (lists[0]) {
    - struct option o = OPT_CALLBACK('e', "event", &trace->evlist, "event",
    - "event selector. use 'perf list' to list available events",
    - parse_events_option);
    + struct option o = {
    + .value = &trace->evlist,
    + };
    err = parse_events_option(&o, lists[0], 0);
    }
    out:
    @@ -3995,9 +3995,12 @@ static int trace__parse_cgroups(const struct option *opt, const char *str, int u
    {
    struct trace *trace = opt->value;

    - if (!list_empty(&trace->evlist->core.entries))
    - return parse_cgroups(opt, str, unset);
    -
    + if (!list_empty(&trace->evlist->core.entries)) {
    + struct option o = {
    + .value = &trace->evlist,
    + };
    + return parse_cgroups(&o, str, unset);
    + }
    trace->cgroup = evlist__findnew_cgroup(trace->evlist, str);

    return 0;
    --
    2.27.0


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