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

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Message-ID: <7d703c4c-1a24-4806-a483-c02efb666059@gmail.com>
Date:   Tue, 24 Oct 2023 19:28:24 -0700
From:   Kui-Feng Lee <sinquersw@...il.com>
To:     Yuran Pereira <yuran.pereira@...mail.com>, yonghong.song@...ux.dev
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

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.

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"))