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

From: Ian Rogers <irogers@google.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	 Tom Rix <trix@redhat.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@kernel.org>,
	 Adrian Hunter <adrian.hunter@intel.com>,
	Yicong Yang <yangyicong@hisilicon.com>,
	 Jonathan Cameron <jonathan.cameron@huawei.com>,
	Yang Jihong <yangjihong1@huawei.com>,
	 Kan Liang <kan.liang@linux.intel.com>,
	Ming Wang <wangming01@loongson.cn>,
	 Huacai Chen <chenhuacai@kernel.org>,
	Sean Christopherson <seanjc@google.com>,
	 K Prateek Nayak <kprateek.nayak@amd.com>,
	Yanteng Si <siyanteng@loongson.cn>,
	 Yuan Can <yuancan@huawei.com>,
	Ravi Bangoria <ravi.bangoria@amd.com>,
	 James Clark <james.clark@arm.com>,
	llvm@lists.linux.dev, linux-kernel@vger.kernel.org,
	 linux-perf-users@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH v2 04/18] perf hisi-ptt: Fix potential memory leak
Date: Mon, 9 Oct 2023 08:45:25 -0700	[thread overview]
Message-ID: <CAP-5=fXtx20VWAVpxAB-HHONx-8MUQKyFm9iSf7ohNBhoESoYg@mail.gmail.com> (raw)
In-Reply-To: <CAM9d7ch4SLLbORdhkanCoPQZX=f-p-HxsYX2YWYbtLR4beD4wg@mail.gmail.com>

On Sun, Oct 8, 2023 at 10:41 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Thu, Oct 5, 2023 at 4:09 PM Ian Rogers <irogers@google.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@google.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
> >