Re: [PATCH v1 2/3] perf probe: Fix libdw memory leak

[Namhyung Kim <namhyung@kernel.org>]

On Wed, Oct 02, 2024 at 12:08:30PM -0700, Ian Rogers wrote:
> On Wed, Oct 2, 2024 at 10:44 AM Namhyung Kim <namhyung@gmail.com> wrote:
> >
> > On Mon, Sep 23, 2024 at 5:37 PM Ian Rogers <irogers@google.com> wrote:
> > >
> > > Add missing dwarf_cfi_end to free memory associated with probe_finder
> > > cfi_eh or cfi_dbg. This addresses leak sanitizer issues seen in:
> > > tools/perf/tests/shell/test_uprobe_from_different_cu.sh
> > >
> > > Fixes: 270bde1e76f4 ("perf probe: Search both .eh_frame and .debug_frame sections for probe location")
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > >  tools/perf/util/probe-finder.c | 5 +++++
> > >  1 file changed, 5 insertions(+)
> > >
> > > diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> > > index 630e16c54ed5..78f34fa0c391 100644
> > > --- a/tools/perf/util/probe-finder.c
> > > +++ b/tools/perf/util/probe-finder.c
> > > @@ -1379,6 +1379,11 @@ int debuginfo__find_trace_events(struct debuginfo *dbg,
> > >         if (ret >= 0 && tf.pf.skip_empty_arg)
> > >                 ret = fill_empty_trace_arg(pev, tf.tevs, tf.ntevs);
> > >
> > > +#if _ELFUTILS_PREREQ(0, 142)
> > > +       dwarf_cfi_end(tf.pf.cfi_eh);
> > > +       dwarf_cfi_end(tf.pf.cfi_dbg);
> > > +#endif
> >
> > This is causing another problem.  Now vfs_getname tests are
> > failing because perf probe aborts.
> 
> I wasn't able to reproduce but largely as the test skips. The variable
> is out of scope after the function so I'm struggling to see what the
> issue is.

I'm seeing this.

  $ sudo ./perf test -v vfs
   91: Add vfs_getname probe to get syscall args filenames:
  --- start ---
  test child forked, pid 3013362
  free(): invalid pointer
  linux/tools/perf/tests/shell/lib/probe_vfs_getname.sh: line 13: 3013380 Aborted                 perf probe -q "vfs_getname=getname_flags:${line} pathname=result->name:string"
  free(): invalid pointer
  linux/tools/perf/tests/shell/lib/probe_vfs_getname.sh: line 13: 3013381 Aborted                 perf probe $add_probe_verbose "vfs_getname=getname_flags:${line} pathname=filename:ustring"
  ---- end(-1) ----
   91: Add vfs_getname probe to get syscall args filenames             : FAILED!
   93: Use vfs_getname probe to get syscall args filenames:
  --- start ---
  test child forked, pid 3013479
  free(): invalid pointer
  linux/tools/perf/tests/shell/lib/probe_vfs_getname.sh: line 13: 3013502 Aborted                 perf probe -q "vfs_getname=getname_flags:${line} pathname=result->name:string"
  free(): invalid pointer
  linux/tools/perf/tests/shell/lib/probe_vfs_getname.sh: line 13: 3013514 Aborted                 perf probe $add_probe_verbose "vfs_getname=getname_flags:${line} pathname=filename:ustring"
  ---- end(-1) ----
   93: Use vfs_getname probe to get syscall args filenames             : FAILED!
  127: Check open filename arg using perf trace + vfs_getname:
  --- start ---
  test child forked, pid 3013528
  free(): invalid pointer
  linux/tools/perf/tests/shell/lib/probe_vfs_getname.sh: line 13: 3013547 Aborted                 perf probe -q "vfs_getname=getname_flags:${line} pathname=result->name:string"
  free(): invalid pointer
  linux/tools/perf/tests/shell/lib/probe_vfs_getname.sh: line 13: 3013548 Aborted                 perf probe $add_probe_verbose "vfs_getname=getname_flags:${line} pathname=filename:ustring"
  ---- end(-1) ----
  127: Check open filename arg using perf trace + vfs_getname          : FAILED!
  
Dropping the series from tmp.perf-tools-next for now.

Thanks,
Namhyung