Re: [PATCH 1/1] perf probe: Free string returned by synthesize_perf_probe_point() on failure to add a probe

From: Google
Date: Sat Aug 05 2023 - 10:01:59 EST


On Fri, 4 Aug 2023 13:22:44 -0300
Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:

> Building perf with EXTRA_CFLAGS="-fsanitize=address" a leak is detect
> when trying to add a probe to a non-existent function:
>
> # perf probe -x ~/bin/perf dso__neW
> Probe point 'dso__neW' not found.
> Error: Failed to add events.
>
> =================================================================
> ==296634==ERROR: LeakSanitizer: detected memory leaks
>
> Direct leak of 128 byte(s) in 1 object(s) allocated from:
> #0 0x7f67642ba097 in calloc (/lib64/libasan.so.8+0xba097)
> #1 0x7f67641a76f1 in allocate_cfi (/lib64/libdw.so.1+0x3f6f1)
>
> Direct leak of 65 byte(s) in 1 object(s) allocated from:
> #0 0x7f67642b95b5 in __interceptor_realloc.part.0 (/lib64/libasan.so.8+0xb95b5)
> #1 0x6cac75 in strbuf_grow util/strbuf.c:64
> #2 0x6ca934 in strbuf_init util/strbuf.c:25
> #3 0x9337d2 in synthesize_perf_probe_point util/probe-event.c:2018
> #4 0x92be51 in try_to_find_probe_trace_events util/probe-event.c:964
> #5 0x93d5c6 in convert_to_probe_trace_events util/probe-event.c:3512
> #6 0x93d6d5 in convert_perf_probe_events util/probe-event.c:3529
> #7 0x56f37f in perf_add_probe_events /var/home/acme/git/perf-tools-next/tools/perf/builtin-probe.c:354
> #8 0x572fbc in __cmd_probe /var/home/acme/git/perf-tools-next/tools/perf/builtin-probe.c:738
> #9 0x5730f2 in cmd_probe /var/home/acme/git/perf-tools-next/tools/perf/builtin-probe.c:766
> #10 0x635d81 in run_builtin /var/home/acme/git/perf-tools-next/tools/perf/perf.c:323
> #11 0x6362c1 in handle_internal_command /var/home/acme/git/perf-tools-next/tools/perf/perf.c:377
> #12 0x63667a in run_argv /var/home/acme/git/perf-tools-next/tools/perf/perf.c:421
> #13 0x636b8d in main /var/home/acme/git/perf-tools-next/tools/perf/perf.c:537
> #14 0x7f676302950f in __libc_start_call_main (/lib64/libc.so.6+0x2950f)
>
> SUMMARY: AddressSanitizer: 193 byte(s) leaked in 2 allocation(s).
> #
>
> synthesize_perf_probe_point() returns a "detached" strbuf, i.e. a
> malloc'ed string that needs to be free'd.
>
> An audit will be performed to find other such cases.

Thanks for finding it!

Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>

>
> Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Cc: Ian Rogers <irogers@xxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Link: https://lore.kernel.org/lkml/
> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> ---
> tools/perf/util/probe-event.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 2d056f02ae408a64..c7bfeab610a3679a 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -961,8 +961,9 @@ static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
> debuginfo__delete(dinfo);
>
> if (ntevs == 0) { /* No error but failed to find probe point. */
> - pr_warning("Probe point '%s' not found.\n",
> - synthesize_perf_probe_point(&pev->point));
> + char *probe_point = synthesize_perf_probe_point(&pev->point);
> + pr_warning("Probe point '%s' not found.\n", probe_point);
> + free(probe_point);
> return -ENODEV;
> } else if (ntevs < 0) {
> /* Error path : ntevs < 0 */
> --
> 2.37.1
>


--
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>