Re: [PATCH bpf-next v3 02/15] selftests/bpf: Bind an exclusive map through a continuous fd_array

["Kumar Kartikeya Dwivedi" <memxor@gmail.com>]

On Fri Oct 16, 2026 at 1:53 AM CEST, sashiko-bot wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] selftests/bpf: missing NULL check for skeleton pointer in test_map_excl_fd_array()
> --
>
> commit 1bd492fc1fe89d69931d1485e93eef135d1cd6e5
> Author: Kumar Kartikeya Dwivedi <memxor@gmail.com>
>
> selftests/bpf: Bind an exclusive map through a continuous fd_array
>
> Load the exclusive program of map_excl with the map in a continuous
> fd_array rather than through its insns alone, which has to work, and
> the other program the same way, which has to be refused. The two
> programs used to be identical and so shared a digest; give the second
> one a value of its own so that the kernel can tell them apart.
>
>> diff --git a/tools/testing/selftests/bpf/prog_tests/map_excl.c b/tools/testing/selftests/bpf/prog_tests/map_excl.c
>> index 3f4422b9ffa69..3592f3ec49490 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/map_excl.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/map_excl.c
>> @@ -161,12 +161,47 @@ static void test_map_excl_create_validation(void)
>>  	ASSERT_EQ(fd, -EINVAL, "reject size with NULL hash pointer");
>>  }
>>
>> +/*
>> + * The exclusive map bound through a continuous fd_array rather than by an
>> + * insn. The kernel resolves the array before it verifies the program, so it
>> + * has to have the digest of the program at hand by then.
>> + */
>> +static void test_map_excl_fd_array(void)
>> +{
>> +	struct map_excl *skel = map_excl__open();
>> +	LIBBPF_OPTS(bpf_prog_load_opts, opts);
>> +	int err, fd, map_fd;
>> +
>> +	err = bpf_map__set_exclusive_program(skel->maps.excl_map, skel->progs.should_have_access);
>
> [Severity: Medium]
> Does this code need to check if skel is NULL before dereferencing it?
>
> If map_excl__open() fails to open the BPF object (for instance, due to
> ENOMEM or a missing object file), it returns a NULL pointer. By passing
> skel->maps.excl_map and skel->progs.should_have_access directly to
> bpf_map__set_exclusive_program(), this will cause a segmentation fault in
> the test runner instead of gracefully reporting a test failure.
>
> Should there be an ASSERT_OK_PTR(skel, "open") check here before proceeding?
>

Should be ok but will follow up or fix in respin.

>> +	if (!ASSERT_OK(err, "bpf_map__set_exclusive_program"))
>> +		goto out;
>> +
>> +	bpf_program__set_autoload(skel->progs.should_have_access, true);
>> +	bpf_program__set_autoload(skel->progs.should_not_have_access, true);
>> +	err = bpf_object__prepare(skel->obj);
>> +	if (!ASSERT_OK(err, "map_excl prepare"))
>> +		goto out;
>
> [ ... ]