linux-kernel - Re: [PATCH bpf-next] selftests/bpf: Add malloc failure checks in bpf

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Date:   Tue, 24 Oct 2023 21:18:08 -0700
From:   Yonghong Song <yonghong.song@...ux.dev>
To:     Kui-Feng Lee <sinquersw@...il.com>,
        Yuran Pereira <yuran.pereira@...mail.com>
Cc:     shuah@...nel.org, ast@...nel.org, daniel@...earbox.net,
        andrii@...nel.org, martin.lau@...ux.dev, song@...nel.org,
        john.fastabend@...il.com, kpsingh@...nel.org, sdf@...gle.com,
        haoluo@...gle.com, jolsa@...nel.org, mykolal@...com,
        brauner@...nel.org, iii@...ux.ibm.com, kuifeng@...a.com,
        bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next] selftests/bpf: Add malloc failure checks in
 bpf_iter


On 10/24/23 7:28 PM, Kui-Feng Lee wrote:
> Thank you for the patches.
>
> I found you have two patches in this set.
> You can generate both patch at once with git format-patch.
> format-patch will give each patch a number in their order.
> For example, the subject of this message will be
>
>   [PATCH bpf-next 2/2] selftest/bpf: Add malloc ....
>
> And, you put both patches in the same directory.  And sent them at once
> by giving the path of the directory. For example,
>
>   git send-email --to=bpf@...r.kernel.org path/to/the/directory/
>
> These patches will be sent in a thread instead of two independent
> messages.


Yuran, second to Kui-Feng's suggestion which is also my original
suggestion although I forgot to explicitly mention that two
patches should be in the same patch set.
I found one issue with the CHECK->ASSERT patch, so please
respin with patch v2 with two patches as the same set.


>
> On 10/24/23 18:52, Yuran Pereira wrote:
>> Since some malloc calls in bpf_iter may at times fail,
>> this patch adds the appropriate fail checks, and ensures that
>> any previously allocated resource is appropriately destroyed
>> before returning the function.
>>
>> This is patch 2 in the sequence should be applied after d1a88d37cecc
>> "selftests/bpf: Convert CHECK macros to ASSERT_* macros in bpf_iter"
>>
>> Patch 1:
>> https://lore.kernel.org/lkml/DB3PR10MB683589A5F705C6CA5BE0D325E8DFA@DB3PR10MB6835.EURPRD10.PROD.OUTLOOK.COM 
>>
>>
>> Signed-off-by: Yuran Pereira <yuran.pereira@...mail.com>
>> ---
>>   tools/testing/selftests/bpf/prog_tests/bpf_iter.c | 10 +++++++++-
>>   1 file changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c 
>> b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
>> index 526ac4e741ee..c6cf42c64af3 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
>> @@ -700,7 +700,7 @@ static void test_overflow(bool 
>> test_e2big_overflow, bool ret1)
>>           goto free_link;
>>         buf = malloc(expected_read_len);
>> -    if (!buf)
>> +    if (!ASSERT_OK_PTR(buf, "malloc"))
>>           goto close_iter;
>>         /* do read */
>> @@ -871,6 +871,10 @@ static void test_bpf_percpu_hash_map(void)
>>         skel->rodata->num_cpus = bpf_num_possible_cpus();
>>       val = malloc(8 * bpf_num_possible_cpus());
>> +    if (!ASSERT_OK_PTR(val, "malloc")) {
>> +        bpf_iter_bpf_percpu_hash_map__destroy(skel);
>> +        return;
>> +    }
>
> You can just do "goto out;" here.
>
>
>>         err = bpf_iter_bpf_percpu_hash_map__load(skel);
>>       if (!ASSERT_OK_PTR(skel, "bpf_iter_bpf_percpu_hash_map__load"))
>> @@ -1048,6 +1052,10 @@ static void test_bpf_percpu_array_map(void)
>>         skel->rodata->num_cpus = bpf_num_possible_cpus();
>>       val = malloc(8 * bpf_num_possible_cpus());
>> +    if (!ASSERT_OK_PTR(val, "malloc")) {
>> +        bpf_iter_bpf_percpu_array_map__destroy(skel);
>> +        return;
>> +    }
>
> Same here, even it will call free(val), free(val) will do nothing when
> val is NULL.
>
>>         err = bpf_iter_bpf_percpu_array_map__load(skel);
>>       if (!ASSERT_OK_PTR(skel, "bpf_iter_bpf_percpu_array_map__load"))