Re: [PATCH 2/3] perf test: fix sys_enter_openat event test for musl

[Martin Kaiser <martin@kaiser.cx>]

Thus wrote Namhyung Kim (namhyung@kernel.org):

> On Mon, Apr 27, 2026 at 09:49:37AM +0000, sashiko-bot@kernel.org wrote:
> > Sashiko AI review found 1 potential issue(s):
> > - [Medium] The updated bitwise check `(tp_flags & flags) != flags` fails to verify the `O_RDONLY` access mode and permits arbitrary unrelated flags, severely weakening the test.
> > --

> > commit 0700122c98ba7f263a329cd8f9fbeef95b67603e
> > Author: Martin Kaiser <martin@kaiser.cx>

> > perf test: fix sys_enter_openat event test for musl

> > This commit updates the sys_enter_openat test to allow additional flags in the
> > captured event. It replaces the strict equality check with a bitwise mask check
> > to accommodate the O_LARGEFILE flag implicitly added by musl libc.

> > > diff --git a/tools/perf/tests/openat-syscall-tp-fields.c b/tools/perf/tests/openat-syscall-tp-fields.c
> > > --- a/tools/perf/tests/openat-syscall-tp-fields.c
> > > +++ b/tools/perf/tests/openat-syscall-tp-fields.c

> > [ ... ]

> > > @@ -120,7 +120,8 @@ static int test__syscall_openat_tp_fields(struct test_suite *test __maybe_unused

> > >  				tp_flags = evsel__intval(evsel, &sample, "flags");
> > >  				perf_sample__exit(&sample);
> > > -				if (flags != tp_flags) {
> > > +				/* C library wrapper may set additional flags */
> > > +				if ((tp_flags & flags) != flags) {

> > Does this check still verify the O_RDONLY access mode?

> > Since O_RDONLY is defined as 0, the flags variable evaluates to exactly
> > O_DIRECTORY. This means the condition functionally becomes
> > (tp_flags & O_DIRECTORY) != O_DIRECTORY.

> > Does this unintentionally permit other access modes like O_WRONLY or O_RDWR,
> > and ignore other unrelated flags as long as O_DIRECTORY is set?

> I think it's ok for tp_flags to have more flags.

I added another check for the access mode flags in v2. This addresses the
sashiko comment and allows for additional flags in the syscall wrapper.

Best regards,
Martin

> Acked-by: Namhyung Kim <namhyung@kernel.org>

> Thanks,
> Namhyung


> > >  					pr_debug("%s: Expected flags=%#x, got %#x\n",
> > >  						 __func__, flags, tp_flags);
> > >  					goto out_delete_evlist;

> > -- 
> > Sashiko AI review · https://sashiko.dev/#/patchset/20260427090225.794482-1-martin@kaiser.cx?part=2