linux-kernel - Re: [PATCH] perf hisi-ptt: Fix memory leak in lseek failure handling

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Date:   Fri, 6 Oct 2023 09:09:59 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Namhyung Kim <namhyung@...nel.org>
CC:     Kuan-Wei Chiu <visitorckw@...il.com>, <yangyicong@...ilicon.com>,
        <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
        <mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
        <jolsa@...nel.org>, <irogers@...gle.com>,
        <adrian.hunter@...el.com>, <linux-kernel@...r.kernel.org>,
        <linux-perf-users@...r.kernel.org>,
        "Ian Rogers" <irogers@...gle.com>
Subject: Re: [PATCH] perf hisi-ptt: Fix memory leak in lseek failure
 handling

On Mon, 2 Oct 2023 21:48:14 -0700
Namhyung Kim <namhyung@...nel.org> wrote:

> Hello,
> 
> On Sat, Sep 30, 2023 at 12:27 AM Kuan-Wei Chiu <visitorckw@...il.com> wrote:
> >
> > In the previous code, there was a memory leak issue where the previously
> > allocated memory was not freed upon a failed lseek operation. This patch
> > addresses the problem by releasing the old memory before returning -errno
> > in case of a lseek failure. This ensures that memory is properly managed
> > and avoids potential memory leaks.
> >
> > Signed-off-by: Kuan-Wei Chiu <visitorckw@...il.com>  
> 
> Acked-by: Namhyung Kim <namhyung@...nel.org>
> 
FYI, Ian Rogers has a series with a similar fix that goes a little further
and drops the assignment of data_offset seen just at the top of the context
below as it is unused.

https://lore.kernel.org/all/20231005230851.3666908-5-irogers@google.com/

I haven't replied to this yet as want to check some related handling
with one of my China based colleagues and it's a festival this week.

One of us will get back on this next week,

Jonathan

> Thanks,
> Namhyung
> 
> 
> > ---
> >  tools/perf/util/hisi-ptt.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/util/hisi-ptt.c b/tools/perf/util/hisi-ptt.c
> > index 45b614bb73bf..43bd1ca62d58 100644
> > --- a/tools/perf/util/hisi-ptt.c
> > +++ b/tools/perf/util/hisi-ptt.c
> > @@ -108,8 +108,10 @@ static int hisi_ptt_process_auxtrace_event(struct perf_session *session,
> >                 data_offset = 0;
> >         } else {
> >                 data_offset = lseek(fd, 0, SEEK_CUR);
> > -               if (data_offset == -1)
> > +               if (data_offset == -1) {
> > +                       free(data);
> >                         return -errno;
> > +               }
> >         }
> >
> >         err = readn(fd, data, size);
> > --
> > 2.25.1
> >  
>