Re: [RFC PATCH] perf util: asprintf helper for leak sanitizer

[Ian Rogers]

On Tue, Jun 13, 2023 at 12:50 PM Arnaldo Carvalho de Melo
<acme@xxxxxxxxxx> wrote:
>
> Em Tue, Jun 13, 2023 at 12:16:38PM -0700, Ian Rogers escreveu:
> > asprintf is a source of memory leaks but produces bad stack traces on
> > my Debian linux. This patch adds a simple asprintf implementation to
> > util.c that works around it.
>
> So is this something to report to the glibc maintainers or debian?

*shrug* Folks appear to have been complaining about no option for
nearly 10 years, motivated by profiling more than sanitizers. Perhaps
I need to convince my employer to switch to Fedora.

Thanks,
Ian

> - Arnaldo
>
> > Before output:
> > ```
> > ==1541752==ERROR: LeakSanitizer: detected memory leaks
> >
> > Direct leak of 10 byte(s) in 1 object(s) allocated from:
> >     #0 0x7f90c76b89cf in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:69
> >     #1 0x7f90c649d2c7 in __vasprintf_internal libio/vasprintf.c:71
> >     #2 0x55ad9b79afbf  (/tmp/perf/perf+0x850fbf)
> >
> > SUMMARY: AddressSanitizer: 10 byte(s) leaked in 1 allocation(s).
> > ```
> >
> > After output:
> > ```
> > ==1545918==ERROR: LeakSanitizer: detected memory leaks
> >
> > Direct leak of 10 byte(s) in 1 object(s) allocated from:
> >     #0 0x7f2755a7077b in __interceptor_strdup ../../../../src/libsanitizer/asan/asan_interceptors.cpp:439
> >     #1 0x564986a8df31 in asprintf util/util.c:566
> >     #2 0x5649869b5901 in metricgroup__lookup_default_metricgroup util/metricgroup.c:1520
> >     #3 0x5649869b5e57 in metricgroup__lookup_create util/metricgroup.c:1579
> >     #4 0x5649869b6ddc in parse_groups util/metricgroup.c:1698
> >     #5 0x5649869b7714 in metricgroup__parse_groups util/metricgroup.c:1771
> >     #6 0x5649867da9d5 in add_default_attributes tools/perf/builtin-stat.c:2164
> >     #7 0x5649867ddbfb in cmd_stat tools/perf/builtin-stat.c:2707
> >     #8 0x5649868fa5a2 in run_builtin tools/perf/perf.c:323
> >     #9 0x5649868fab13 in handle_internal_command tools/perf/perf.c:377
> >     #10 0x5649868faedb in run_argv tools/perf/perf.c:421
> >     #11 0x5649868fb443 in main tools/perf/perf.c:537
> >     #12 0x7f2754846189 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
> >
> > SUMMARY: AddressSanitizer: 10 byte(s) leaked in 1 allocation(s).
> > ```
> >
> > RFC: is this useful for others? Should we have a build flag for it?
> > ---
> >  tools/perf/util/util.c | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
> > index c1fd9ba6d697..57eb528c5fed 100644
> > --- a/tools/perf/util/util.c
> > +++ b/tools/perf/util/util.c
> > @@ -552,3 +552,22 @@ int sched_getcpu(void)
> >       return -1;
> >  }
> >  #endif
> > +
> > +int asprintf(char **restrict strp, const char *restrict fmt, ...)
> > +{
> > +     char buf[1024];
> > +     va_list ap;
> > +     int size;
> > +     char *result;
> > +
> > +     va_start(ap, fmt);
> > +     size = vsnprintf(buf, sizeof(buf), fmt, ap);
> > +     if (size < (int)sizeof(buf))
> > +             result = strdup(buf);
> > +     else
> > +             size = vasprintf(&result, fmt, ap);
> > +
> > +     *strp = result;
> > +     va_end(ap);
> > +     return size;
> > +}
> > --
> > 2.41.0.162.gfafddb0af9-goog
> >
>
> --
>
> - Arnaldo