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

From: Namhyung Kim
Date: Wed Oct 02 2024 - 17:54:09 EST


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@xxxxxxxxx> wrote:
> >
> > On Mon, Sep 23, 2024 at 5:37 PM Ian Rogers <irogers@xxxxxxxxxx> 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@xxxxxxxxxx>
> > > ---
> > > 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