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Subject: Re: [PATCH bpf-next 4/4] selftests/bpf: Add a null pointer check for
 the serial_test_tp_attach_query
From: Daniel Borkmann <daniel@iogearbox.net>
To: Kunwu Chan <chentao@kylinos.cn>, ast@kernel.org, andrii@kernel.org,
 martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org,
 yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org,
 sdf@google.com, haoluo@google.com, jolsa@kernel.org, mykolal@fb.com,
 shuah@kernel.org, kunwu.chan@hotmail.com
Cc: bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
 linux-kernel@vger.kernel.org
References: <20240424020444.2375773-1-chentao@kylinos.cn>
 <20240424020444.2375773-5-chentao@kylinos.cn>
 <79df3541-5557-05fa-a81e-84728d509bfc@iogearbox.net>
Message-ID: <57c18a4f-24bb-24fe-b3f3-33b3987fb393@iogearbox.net>
Date: Fri, 3 May 2024 17:51:29 +0200
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On 5/3/24 5:47 PM, Daniel Borkmann wrote:
> On 4/24/24 4:04 AM, Kunwu Chan wrote:
>> There is a 'malloc' call, which can be unsuccessful.
>> Add the malloc failure checking to avoid possible null
>> dereference.
>>
>> Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
>> ---
>>   tools/testing/selftests/bpf/prog_tests/tp_attach_query.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
>> index 655d69f0ff0b..302b25408a53 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
>> @@ -39,6 +39,9 @@ void serial_test_tp_attach_query(void)
>>       attr.wakeup_events = 1;
>>       query = malloc(sizeof(*query) + sizeof(__u32) * num_progs);
>> +    if (CHECK(!query, "malloc()", "error:%s\n", strerror(errno)))
> 
> Series looks reasonable, small nit on CHECK() : Lets use ASSERT*() macros given they are
> preferred over the latter :
> 
> if (!ASSERT_OK_PTR(buf, "malloc"))

( Also as a side-note: Fixes tag on all these patches is not needed given this will just
   end up spamming stable tree. If you indeed end up with NULL then the tests will just
   segfault & fail. )

>> +        return;
>> +
>>       for (i = 0; i < num_progs; i++) {
>>           err = bpf_prog_test_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj[i],
>>                       &prog_fd[i]);
>>
>