linux-kernel - Re: [PATCH v2 04/18] perf hisi-ptt: Fix potential memory leak

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Date:   Mon, 9 Oct 2023 08:45:25 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Yicong Yang <yangyicong@...ilicon.com>,
        Jonathan Cameron <jonathan.cameron@...wei.com>,
        Yang Jihong <yangjihong1@...wei.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Ming Wang <wangming01@...ngson.cn>,
        Huacai Chen <chenhuacai@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        K Prateek Nayak <kprateek.nayak@....com>,
        Yanteng Si <siyanteng@...ngson.cn>,
        Yuan Can <yuancan@...wei.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        James Clark <james.clark@....com>, llvm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [PATCH v2 04/18] perf hisi-ptt: Fix potential memory leak

On Sun, Oct 8, 2023 at 10:41 PM Namhyung Kim <namhyung@...nel.org> wrote:
>
> On Thu, Oct 5, 2023 at 4:09 PM Ian Rogers <irogers@...gle.com> wrote:
> >
> > Fix clang-tidy found potential memory leak and unread value:
> > ```
> > tools/perf/util/hisi-ptt.c:108:3: warning: Value stored to 'data_offset' is never read [clang-analyzer-deadcode.DeadStores]
> >                 data_offset = 0;
> >                 ^             ~
> > tools/perf/util/hisi-ptt.c:108:3: note: Value stored to 'data_offset' is never read
> >                 data_offset = 0;
> >                 ^             ~
> > tools/perf/util/hisi-ptt.c:112:12: warning: Potential leak of memory pointed to by 'data' [clang-analyzer-unix.Malloc]
> >                         return -errno;
> >                                 ^
> > /usr/include/errno.h:38:18: note: expanded from macro 'errno'
> >                  ^
> > tools/perf/util/hisi-ptt.c:100:15: note: Memory is allocated
> >         void *data = malloc(size);
> >                      ^~~~~~~~~~~~
> > tools/perf/util/hisi-ptt.c:104:6: note: Assuming 'data' is non-null
> >         if (!data)
> >             ^~~~~
> > tools/perf/util/hisi-ptt.c:104:2: note: Taking false branch
> >         if (!data)
> >         ^
> > tools/perf/util/hisi-ptt.c:107:6: note: Assuming the condition is false
> >         if (perf_data__is_pipe(session->data)) {
> >             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > tools/perf/util/hisi-ptt.c:107:2: note: Taking false branch
> >         if (perf_data__is_pipe(session->data)) {
> >         ^
> > tools/perf/util/hisi-ptt.c:111:7: note: Assuming the condition is true
> >                 if (data_offset == -1)
> >                     ^~~~~~~~~~~~~~~~~
> > tools/perf/util/hisi-ptt.c:111:3: note: Taking true branch
> >                 if (data_offset == -1)
> >                 ^
> > tools/perf/util/hisi-ptt.c:112:12: note: Potential leak of memory pointed to by 'data'
> >                         return -errno;
> >                                 ^
> > /usr/include/errno.h:38:18: note: expanded from macro 'errno'
> > ```
>
> We already have
>
>   https://lore.kernel.org/r/20230930072719.1267784-1-visitorckw@gmail.com

Agreed. There is a written to but not read addressed in this one, but
I think that is okay to clean up later and to drop this patch.

Thanks,
Ian

> Thanks,
> Namhyung
>
>
> >
> > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > ---
> >  tools/perf/util/hisi-ptt.c | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/tools/perf/util/hisi-ptt.c b/tools/perf/util/hisi-ptt.c
> > index 45b614bb73bf..ea297329c526 100644
> > --- a/tools/perf/util/hisi-ptt.c
> > +++ b/tools/perf/util/hisi-ptt.c
> > @@ -98,18 +98,18 @@ static int hisi_ptt_process_auxtrace_event(struct perf_session *session,
> >         int fd = perf_data__fd(session->data);
> >         int size = event->auxtrace.size;
> >         void *data = malloc(size);
> > -       off_t data_offset;
> >         int err;
> >
> >         if (!data)
> >                 return -errno;
> >
> > -       if (perf_data__is_pipe(session->data)) {
> > -               data_offset = 0;
> > -       } else {
> > -               data_offset = lseek(fd, 0, SEEK_CUR);
> > -               if (data_offset == -1)
> > +       if (!perf_data__is_pipe(session->data)) {
> > +               off_t data_offset = lseek(fd, 0, SEEK_CUR);
> > +
> > +               if (data_offset == -1) {
> > +                       free(data);
> >                         return -errno;
> > +               }
> >         }
> >
> >         err = readn(fd, data, size);
> > --
> > 2.42.0.609.gbb76f46606-goog
> >