Re: [PATCH v2 17/18] perf header: Fix various error path memory leaks

[Namhyung Kim <namhyung@kernel.org>]

On Thu, Oct 5, 2023 at 4:09 PM Ian Rogers <irogers@google.com> wrote:
>
> Memory leaks were detected by clang-tidy.
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/util/header.c | 63 ++++++++++++++++++++++++----------------
>  1 file changed, 38 insertions(+), 25 deletions(-)
>
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index d812e1e371a7..41b78e40b22b 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -2598,8 +2598,10 @@ static int process_cpu_topology(struct feat_fd *ff, void *data __maybe_unused)
>                         goto error;
>
>                 /* include a NULL character at the end */
> -               if (strbuf_add(&sb, str, strlen(str) + 1) < 0)
> +               if (strbuf_add(&sb, str, strlen(str) + 1) < 0) {
> +                       free(str);
>                         goto error;
> +               }
>                 size += string_size(str);
>                 free(str);
>         }
> @@ -2617,8 +2619,10 @@ static int process_cpu_topology(struct feat_fd *ff, void *data __maybe_unused)
>                         goto error;
>
>                 /* include a NULL character at the end */
> -               if (strbuf_add(&sb, str, strlen(str) + 1) < 0)
> +               if (strbuf_add(&sb, str, strlen(str) + 1) < 0) {
> +                       free(str);
>                         goto error;
> +               }
>                 size += string_size(str);
>                 free(str);
>         }
> @@ -2681,8 +2685,10 @@ static int process_cpu_topology(struct feat_fd *ff, void *data __maybe_unused)
>                         goto error;
>
>                 /* include a NULL character at the end */
> -               if (strbuf_add(&sb, str, strlen(str) + 1) < 0)
> +               if (strbuf_add(&sb, str, strlen(str) + 1) < 0) {
> +                       free(str);
>                         goto error;
> +               }
>                 size += string_size(str);
>                 free(str);
>         }

For these cases, it'd be simpler to free it in the error path.


> @@ -2736,10 +2742,9 @@ static int process_numa_topology(struct feat_fd *ff, void *data __maybe_unused)
>                         goto error;
>
>                 n->map = perf_cpu_map__new(str);
> +               free(str);
>                 if (!n->map)
>                         goto error;
> -
> -               free(str);
>         }
>         ff->ph->env.nr_numa_nodes = nr;
>         ff->ph->env.numa_nodes = nodes;
> @@ -2913,10 +2918,10 @@ static int process_cache(struct feat_fd *ff, void *data __maybe_unused)
>                 return -1;
>
>         for (i = 0; i < cnt; i++) {
> -               struct cpu_cache_level c;
> +               struct cpu_cache_level *c = &caches[i];
>
>                 #define _R(v)                                           \
> -                       if (do_read_u32(ff, &c.v))\
> +                       if (do_read_u32(ff, &c->v))                     \
>                                 goto out_free_caches;                   \
>
>                 _R(level)
> @@ -2926,22 +2931,25 @@ static int process_cache(struct feat_fd *ff, void *data __maybe_unused)
>                 #undef _R
>
>                 #define _R(v)                                   \
> -                       c.v = do_read_string(ff);               \
> -                       if (!c.v)                               \
> -                               goto out_free_caches;
> +                       c->v = do_read_string(ff);              \
> +                       if (!c->v)                              \
> +                               goto out_free_caches;           \
>
>                 _R(type)
>                 _R(size)
>                 _R(map)
>                 #undef _R
> -
> -               caches[i] = c;
>         }
>
>         ff->ph->env.caches = caches;
>         ff->ph->env.caches_cnt = cnt;
>         return 0;
>  out_free_caches:
> +       for (i = 0; i < cnt; i++) {
> +               free(caches[i].type);
> +               free(caches[i].size);
> +               free(caches[i].map);
> +       }
>         free(caches);
>         return -1;
>  }

Looks ok.


> @@ -3585,18 +3593,16 @@ static int perf_header__adds_write(struct perf_header *header,
>                                    struct feat_copier *fc)
>  {
>         int nr_sections;
> -       struct feat_fd ff;
> +       struct feat_fd ff = {
> +               .fd  = fd,
> +               .ph = header,
> +       };

I'm fine with this change.


>         struct perf_file_section *feat_sec, *p;
>         int sec_size;
>         u64 sec_start;
>         int feat;
>         int err;
>
> -       ff = (struct feat_fd){
> -               .fd  = fd,
> -               .ph = header,
> -       };
> -
>         nr_sections = bitmap_weight(header->adds_features, HEADER_FEAT_BITS);
>         if (!nr_sections)
>                 return 0;
> @@ -3623,6 +3629,7 @@ static int perf_header__adds_write(struct perf_header *header,
>         err = do_write(&ff, feat_sec, sec_size);
>         if (err < 0)
>                 pr_debug("failed to write feature section\n");
> +       free(ff.buf);

But it looks like false alarams.  Since the feat_fd has fd
and no buf, it won't allocate the buffer in do_write() and
just use __do_write_fd().  So no need to free the buf.

Thanks,
Namhyung


>         free(feat_sec);
>         return err;
>  }
> @@ -3630,11 +3637,11 @@ static int perf_header__adds_write(struct perf_header *header,
>  int perf_header__write_pipe(int fd)
>  {
>         struct perf_pipe_file_header f_header;
> -       struct feat_fd ff;
> +       struct feat_fd ff = {
> +               .fd = fd,
> +       };
>         int err;
>
> -       ff = (struct feat_fd){ .fd = fd };
> -
>         f_header = (struct perf_pipe_file_header){
>                 .magic     = PERF_MAGIC,
>                 .size      = sizeof(f_header),
> @@ -3645,7 +3652,7 @@ int perf_header__write_pipe(int fd)
>                 pr_debug("failed to write perf pipe header\n");
>                 return err;
>         }
> -
> +       free(ff.buf);
>         return 0;
>  }
>
> @@ -3658,11 +3665,12 @@ static int perf_session__do_write_header(struct perf_session *session,
>         struct perf_file_attr   f_attr;
>         struct perf_header *header = &session->header;
>         struct evsel *evsel;
> -       struct feat_fd ff;
> +       struct feat_fd ff = {
> +               .fd = fd,
> +       };
>         u64 attr_offset;
>         int err;
>
> -       ff = (struct feat_fd){ .fd = fd};
>         lseek(fd, sizeof(f_header), SEEK_SET);
>
>         evlist__for_each_entry(session->evlist, evsel) {
> @@ -3670,6 +3678,7 @@ static int perf_session__do_write_header(struct perf_session *session,
>                 err = do_write(&ff, evsel->core.id, evsel->core.ids * sizeof(u64));
>                 if (err < 0) {
>                         pr_debug("failed to write perf header\n");
> +                       free(ff.buf);
>                         return err;
>                 }
>         }
> @@ -3695,6 +3704,7 @@ static int perf_session__do_write_header(struct perf_session *session,
>                 err = do_write(&ff, &f_attr, sizeof(f_attr));
>                 if (err < 0) {
>                         pr_debug("failed to write perf header attribute\n");
> +                       free(ff.buf);
>                         return err;
>                 }
>         }
> @@ -3705,8 +3715,10 @@ static int perf_session__do_write_header(struct perf_session *session,
>
>         if (at_exit) {
>                 err = perf_header__adds_write(header, evlist, fd, fc);
> -               if (err < 0)
> +               if (err < 0) {
> +                       free(ff.buf);
>                         return err;
> +               }
>         }
>
>         f_header = (struct perf_file_header){
> @@ -3728,6 +3740,7 @@ static int perf_session__do_write_header(struct perf_session *session,
>
>         lseek(fd, 0, SEEK_SET);
>         err = do_write(&ff, &f_header, sizeof(f_header));
> +       free(ff.buf);
>         if (err < 0) {
>                 pr_debug("failed to write perf header\n");
>                 return err;
> --
> 2.42.0.609.gbb76f46606-goog
>