Re: [PATCH] perf header: Fix memory leaks

[Jiri Olsa <jolsa@redhat.com>]

On Mon, Nov 29, 2021 at 03:38:28PM -0800, Ian Rogers wrote:
> On Sun, Nov 28, 2021 at 7:47 AM Jiri Olsa <jolsa@redhat.com> wrote:
> >
> > On Thu, Nov 18, 2021 at 12:17:30PM -0800, Ian Rogers wrote:
> > > These leaks were found with leak sanitizer running "perf pipe recording
> > > and injection test". In pipe mode feat_fd may hold onto an events struct
> > > that needs freeing. When string features are processed they may
> > > overwrite an already created string, so free this before the overwrite.
> > >
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > >  tools/perf/util/header.c | 15 ++++++++++-----
> > >  1 file changed, 10 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> > > index 79cce216727e..e3c1a532d059 100644
> > > --- a/tools/perf/util/header.c
> > > +++ b/tools/perf/util/header.c
> > > @@ -2321,6 +2321,7 @@ static int perf_header__read_build_ids(struct perf_header *header,
> > >  #define FEAT_PROCESS_STR_FUN(__feat, __feat_env) \
> > >  static int process_##__feat(struct feat_fd *ff, void *data __maybe_unused) \
> > >  {\
> > > +     free(ff->ph->env.__feat_env);                \
> >
> > hm, how is this set before this callback is triggered?
> 
> I see it for cpuid which is initially set in:
> #0  perf_env__read_cpuid (env=0x62b000007240) at util/env.c:363
> #1  0x0000555556325153 in perf_env__cpuid (env=0x62b000007240) at util/env.c:456
> #2  0x00005555564002ff in evlist__init_trace_event_sample_raw

ok, I forgot we do this one, thanks for explanation

Acked-by: Jiri Olsa <jolsa@redhat.com>

jirka


> (evlist=0x61e000000080) at util/sample-raw.c:17
> #3  0x00005555563f01f4 in __perf_session__new (data=0x7fffffffb8b0,
> repipe=false, repipe_fd=-1, tool=0x7fffffffbaa0)
>     at util/session.c:228
> #4  0x000055555615f26b in perf_session__new (data=0x7fffffffb8b0,
> tool=0x7fffffffbaa0) at util/session.h:70
> #5  0x000055555616d991 in cmd_report (argc=0, argv=0x7fffffffe468) at
> builtin-report.c:1408
> #6  0x00005555562f36b8 in run_builtin (p=0x5555586bacd0
> <commands+240>, argc=5, argv=0x7fffffffe468) at perf.c:313
> #7  0x00005555562f3c11 in handle_internal_command (argc=5,
> argv=0x7fffffffe468) at perf.c:365
> #8  0x00005555562f3fce in run_argv (argcp=0x7fffffffe240,
> argv=0x7fffffffe250) at perf.c:409
> #9  0x00005555562f47bd in main (argc=5, argv=0x7fffffffe468) at perf.c:539
> 
> And then overwritten causing the leak:
> #0  0x00005555563b965a in process_cpuid (ff=0x7fffffffad50, data=0x0)
> at util/header.c:2333
> #1  0x00005555563c53d2 in perf_event__process_feature
> (session=0x62b000007200, event=0x621000006500) at util/header.c:4144
> #2  0x000055555615fdef in process_feature_event
> (session=0x62b000007200, event=0x621000006500) at builtin-report.c:230
> #3  0x00005555563fa033 in perf_session__process_user_event
> (session=0x62b000007200, event=0x621000006500, file_offset=868)
>     at util/session.c:1668
> #4  0x00005555563fae08 in perf_session__process_event
> (session=0x62b000007200, event=0x621000006500, file_offset=868)
>     at util/session.c:1803
> #5  0x00005555563fc4e6 in __perf_session__process_pipe_events
> (session=0x62b000007200) at util/session.c:2044
> #6  0x00005555563ff005 in perf_session__process_events
> (session=0x62b000007200) at util/session.c:2418
> #7  0x000055555616508a in __cmd_report (rep=0x7fffffffbaa0) at
> builtin-report.c:940
> #8  0x000055555616f5c9 in cmd_report (argc=0, argv=0x7fffffffe468) at
> builtin-report.c:1629
> #9  0x00005555562f36b8 in run_builtin (p=0x5555586bacd0
> <commands+240>, argc=5, argv=0x7fffffffe468) at perf.c:313
> #10 0x00005555562f3c11 in handle_internal_command (argc=5,
> argv=0x7fffffffe468) at perf.c:365
> #11 0x00005555562f3fce in run_argv (argcp=0x7fffffffe240,
> argv=0x7fffffffe250) at perf.c:409
> #12 0x00005555562f47bd in main (argc=5, argv=0x7fffffffe468) at perf.c:539
> 
> Thanks,
> Ian
> 
> > jirka
> >
> > >       ff->ph->env.__feat_env = do_read_string(ff); \
> > >       return ff->ph->env.__feat_env ? 0 : -ENOMEM; \
> > >  }
> > > @@ -4124,6 +4125,7 @@ int perf_event__process_feature(struct perf_session *session,
> > >       struct perf_record_header_feature *fe = (struct perf_record_header_feature *)event;
> > >       int type = fe->header.type;
> > >       u64 feat = fe->feat_id;
> > > +     int ret = 0;
> > >
> > >       if (type < 0 || type >= PERF_RECORD_HEADER_MAX) {
> > >               pr_warning("invalid record type %d in pipe-mode\n", type);
> > > @@ -4141,11 +4143,13 @@ int perf_event__process_feature(struct perf_session *session,
> > >       ff.size = event->header.size - sizeof(*fe);
> > >       ff.ph = &session->header;
> > >
> > > -     if (feat_ops[feat].process(&ff, NULL))
> > > -             return -1;
> > > +     if (feat_ops[feat].process(&ff, NULL)) {
> > > +             ret = -1;
> > > +             goto out;
> > > +     }
> > >
> > >       if (!feat_ops[feat].print || !tool->show_feat_hdr)
> > > -             return 0;
> > > +             goto out;
> > >
> > >       if (!feat_ops[feat].full_only ||
> > >           tool->show_feat_hdr >= SHOW_FEAT_HEADER_FULL_INFO) {
> > > @@ -4154,8 +4158,9 @@ int perf_event__process_feature(struct perf_session *session,
> > >               fprintf(stdout, "# %s info available, use -I to display\n",
> > >                       feat_ops[feat].name);
> > >       }
> > > -
> > > -     return 0;
> > > +out:
> > > +     free_event_desc(ff.events);
> > > +     return ret;
> > >  }
> > >
> > >  size_t perf_event__fprintf_event_update(union perf_event *event, FILE *fp)
> > > --
> > > 2.34.0.rc2.393.gf8c9666880-goog
> > >
> >
>