Re: [PATCH 07/11] perf tools: Add O_CLOEXEC to open() calls in DSO and ELF code

[Ian Rogers]

On Mon, Jun 8, 2026 at 1:18 PM Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
>
> From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
>
> open() calls in dso.c and symbol-elf.c omit O_CLOEXEC, which leaks
> file descriptors to child processes spawned during symbol resolution
> (e.g., addr2line, objdump).  This can exhaust the fd limit during
> long profiling sessions or when processing many DSOs.
>
> Add O_CLOEXEC to all open() calls in both files (12 call sites).
>
> Fixes: cdd059d731eeb466 ("perf tools: Move dso_* related functions into dso object")
> Fixes: e5a1845fc0aeca85 ("perf symbols: Split out util/symbol-elf.c")
> Reported-by: sashiko-bot <sashiko-bot@xxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Assisted-by: Claude Opus 4.6 <noreply@xxxxxxxxxxxxx>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>
and Sashiko is asking for more of this goodness.

Thanks,
Ian

> ---
>  tools/perf/util/dso.c        |  4 ++--
>  tools/perf/util/symbol-elf.c | 20 ++++++++++----------
>  2 files changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
> index 7dced896c64eafd7..fb2e78fe2aa8eb94 100644
> --- a/tools/perf/util/dso.c
> +++ b/tools/perf/util/dso.c
> @@ -344,7 +344,7 @@ int filename__decompress(const char *name, char *pathname,
>          * descriptor to the uncompressed file.
>          */
>         if (!compressions[comp].is_compressed(name))
> -               return open(name, O_RDONLY);
> +               return open(name, O_RDONLY | O_CLOEXEC);
>
>         fd = mkstemp(tmpbuf);
>         if (fd < 0) {
> @@ -1911,7 +1911,7 @@ static const u8 *__dso__read_symbol(struct dso *dso, const char *symfs_filename,
>         int saved_errno;
>
>         nsinfo__mountns_enter(dso__nsinfo(dso), &nsc);
> -       fd = open(symfs_filename, O_RDONLY);
> +       fd = open(symfs_filename, O_RDONLY | O_CLOEXEC);
>         saved_errno = errno;
>         nsinfo__mountns_exit(&nsc);
>         if (fd < 0) {
> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> index 186e6d92ac3d7742..c2bdfd0003df2abe 100644
> --- a/tools/perf/util/symbol-elf.c
> +++ b/tools/perf/util/symbol-elf.c
> @@ -217,7 +217,7 @@ bool filename__has_section(const char *filename, const char *sec)
>         GElf_Shdr shdr;
>         bool found = false;
>
> -       fd = open(filename, O_RDONLY);
> +       fd = open(filename, O_RDONLY | O_CLOEXEC);
>         if (fd < 0)
>                 return false;
>
> @@ -872,7 +872,7 @@ static int read_build_id(const char *filename, struct build_id *bid)
>         if (size < BUILD_ID_SIZE)
>                 goto out;
>
> -       fd = open(filename, O_RDONLY);
> +       fd = open(filename, O_RDONLY | O_CLOEXEC);
>         if (fd < 0)
>                 goto out;
>
> @@ -935,7 +935,7 @@ int sysfs__read_build_id(const char *filename, struct build_id *bid)
>         size_t size = sizeof(bid->data);
>         int fd, err = -1;
>
> -       fd = open(filename, O_RDONLY);
> +       fd = open(filename, O_RDONLY | O_CLOEXEC);
>         if (fd < 0)
>                 goto out;
>
> @@ -995,7 +995,7 @@ int filename__read_debuglink(const char *filename, char *debuglink,
>         if (err >= 0)
>                 goto out;
>
> -       fd = open(filename, O_RDONLY);
> +       fd = open(filename, O_RDONLY | O_CLOEXEC);
>         if (fd < 0)
>                 goto out;
>
> @@ -1153,7 +1153,7 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
>
>                 type = dso__symtab_type(dso);
>         } else {
> -               fd = open(name, O_RDONLY);
> +               fd = open(name, O_RDONLY | O_CLOEXEC);
>                 if (fd < 0) {
>                         *dso__load_errno(dso) = errno;
>                         return -1;
> @@ -1952,7 +1952,7 @@ static int kcore__open(struct kcore *kcore, const char *filename)
>  {
>         GElf_Ehdr *ehdr;
>
> -       kcore->fd = open(filename, O_RDONLY);
> +       kcore->fd = open(filename, O_RDONLY | O_CLOEXEC);
>         if (kcore->fd == -1)
>                 return -1;
>
> @@ -1985,7 +1985,7 @@ static int kcore__init(struct kcore *kcore, char *filename, int elfclass,
>         if (temp)
>                 kcore->fd = mkstemp(filename);
>         else
> -               kcore->fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0400);
> +               kcore->fd = open(filename, O_WRONLY | O_CREAT | O_EXCL | O_CLOEXEC, 0400);
>         if (kcore->fd == -1)
>                 return -1;
>
> @@ -2461,11 +2461,11 @@ static int kcore_copy__compare_files(const char *from_filename,
>  {
>         int from, to, err = -1;
>
> -       from = open(from_filename, O_RDONLY);
> +       from = open(from_filename, O_RDONLY | O_CLOEXEC);
>         if (from < 0)
>                 return -1;
>
> -       to = open(to_filename, O_RDONLY);
> +       to = open(to_filename, O_RDONLY | O_CLOEXEC);
>         if (to < 0)
>                 goto out_close_from;
>
> @@ -2883,7 +2883,7 @@ int get_sdt_note_list(struct list_head *head, const char *target)
>         Elf *elf;
>         int fd, ret;
>
> -       fd = open(target, O_RDONLY);
> +       fd = open(target, O_RDONLY | O_CLOEXEC);
>         if (fd < 0)
>                 return -EBADF;
>
> --
> 2.54.0
>