selftests/bpf: Fix resource leak in serial_test_wq on attach failure

[PATCH bpf] selftests/bpf: Fix resource leak in serial_test_wq on attach failure

Posted by Kery Qi 2 weeks, 3 days ago

When wq__attach() fails, serial_test_wq() returns early without calling
wq__destroy(), leaking the skeleton resources allocated by
wq__open_and_load(). This causes ASAN leak reports in selftests runs.

Fix this by jumping to a common clean_up label that calls wq__destroy()
on all exit paths after successful open_and_load.

Note that the early return after wq__open_and_load() failure is correct
and doesn't need fixing, since that function returns NULL on failure
(after internally cleaning up any partial allocations).

Fixes: 8290dba51910 ("selftests/bpf: wq: add bpf_wq_start() checks")
Signed-off-by: Kery Qi <qikeyu2017@gmail.com>
---
 tools/testing/selftests/bpf/prog_tests/wq.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/wq.c b/tools/testing/selftests/bpf/prog_tests/wq.c
index 15c67d23128b..84831eecc935 100644
--- a/tools/testing/selftests/bpf/prog_tests/wq.c
+++ b/tools/testing/selftests/bpf/prog_tests/wq.c
@@ -16,12 +16,12 @@ void serial_test_wq(void)
 	/* re-run the success test to check if the timer was actually executed */
 
 	wq_skel = wq__open_and_load();
-	if (!ASSERT_OK_PTR(wq_skel, "wq_skel_load"))
+	if (!ASSERT_OK_PTR(wq_skel, "wq__open_and_load"))
 		return;
 
 	err = wq__attach(wq_skel);
 	if (!ASSERT_OK(err, "wq_attach"))
-		return;
+		goto clean_up;
 
 	prog_fd = bpf_program__fd(wq_skel->progs.test_syscall_array_sleepable);
 	err = bpf_prog_test_run_opts(prog_fd, &topts);
@@ -31,6 +31,7 @@ void serial_test_wq(void)
 	usleep(50); /* 10 usecs should be enough, but give it extra */
 
 	ASSERT_EQ(wq_skel->bss->ok_sleepable, (1 << 1), "ok_sleepable");
+clean_up:
 	wq__destroy(wq_skel);
 }
 
-- 
2.34.1

Re: [PATCH bpf] selftests/bpf: Fix resource leak in serial_test_wq on attach failure

Posted by Yonghong Song 2 weeks, 3 days ago


On 1/21/26 1:41 AM, Kery Qi wrote:
> When wq__attach() fails, serial_test_wq() returns early without calling
> wq__destroy(), leaking the skeleton resources allocated by
> wq__open_and_load(). This causes ASAN leak reports in selftests runs.
>
> Fix this by jumping to a common clean_up label that calls wq__destroy()
> on all exit paths after successful open_and_load.
>
> Note that the early return after wq__open_and_load() failure is correct
> and doesn't need fixing, since that function returns NULL on failure
> (after internally cleaning up any partial allocations).
>
> Fixes: 8290dba51910 ("selftests/bpf: wq: add bpf_wq_start() checks")
> Signed-off-by: Kery Qi <qikeyu2017@gmail.com>

Acked-by: Yonghong Song <yonghong.song@linux.dev>

Re: [PATCH bpf] selftests/bpf: Fix resource leak in serial_test_wq on attach failure

Posted by Kery Qi 2 weeks, 3 days ago

Hi,

Thank you for the review.

You are completely right regarding wq__open_and_load(): if it fails,
it returns NULL and performs its own cleanup, so an immediate return
is correct there.

However, my concern is about the next step: wq__attach(wq_skel).

If wq__open_and_load() succeeds, wq_skel is allocated. If wq__attach()
subsequently fails, the original code returns immediately without
calling wq__destroy(wq_skel), which causes a memory leak of the
skeleton object.

The proposed goto clean_up is intended to ensure wq__destroy(wq_skel)
is called specifically when wq__attach() fails.

Does that make sense?

Best regards,

Kery

Yonghong Song <yonghong.song@linux.dev> 于2026年1月21日周三 23:45写道：
>
>
>
> On 1/21/26 1:41 AM, Kery Qi wrote:
> > When wq__attach() fails, serial_test_wq() returns early without calling
> > wq__destroy(), leaking the skeleton resources allocated by
> > wq__open_and_load(). This causes ASAN leak reports in selftests runs.
> >
> > Fix this by jumping to a common clean_up label that calls wq__destroy()
> > on all exit paths after successful open_and_load.
> >
> > Note that the early return after wq__open_and_load() failure is correct
> > and doesn't need fixing, since that function returns NULL on failure
> > (after internally cleaning up any partial allocations).
> >
> > Fixes: 8290dba51910 ("selftests/bpf: wq: add bpf_wq_start() checks")
> > Signed-off-by: Kery Qi <qikeyu2017@gmail.com>
>
> Acked-by: Yonghong Song <yonghong.song@linux.dev>
>

Re: [PATCH bpf] selftests/bpf: Fix resource leak in serial_test_wq on attach failure

Posted by Yonghong Song 2 weeks, 3 days ago


On 1/21/26 9:49 AM, Kery Qi wrote:
> Hi,
>
> Thank you for the review.
>
> You are completely right regarding wq__open_and_load(): if it fails,
> it returns NULL and performs its own cleanup, so an immediate return
> is correct there.
>
> However, my concern is about the next step: wq__attach(wq_skel).
>
> If wq__open_and_load() succeeds, wq_skel is allocated. If wq__attach()
> subsequently fails, the original code returns immediately without
> calling wq__destroy(wq_skel), which causes a memory leak of the
> skeleton object.
>
> The proposed goto clean_up is intended to ensure wq__destroy(wq_skel)
> is called specifically when wq__attach() fails.
>
> Does that make sense?

Yes.

>
> Best regards,
>
> Kery
>
> Yonghong Song <yonghong.song@linux.dev> 于2026年1月21日周三 23:45写道：
>>
>>
>> On 1/21/26 1:41 AM, Kery Qi wrote:
>>> When wq__attach() fails, serial_test_wq() returns early without calling
>>> wq__destroy(), leaking the skeleton resources allocated by
>>> wq__open_and_load(). This causes ASAN leak reports in selftests runs.
>>>
>>> Fix this by jumping to a common clean_up label that calls wq__destroy()
>>> on all exit paths after successful open_and_load.
>>>
>>> Note that the early return after wq__open_and_load() failure is correct
>>> and doesn't need fixing, since that function returns NULL on failure
>>> (after internally cleaning up any partial allocations).
>>>
>>> Fixes: 8290dba51910 ("selftests/bpf: wq: add bpf_wq_start() checks")
>>> Signed-off-by: Kery Qi <qikeyu2017@gmail.com>
>> Acked-by: Yonghong Song <yonghong.song@linux.dev>
>>