linux-kernel - Re: [PATCH] selftests/bpf: Fix incorrect parameters in NULL pointer checking

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Message-ID: <b6e8187c-c0d0-08d0-ad6f-472155e8b8e9@linux.dev>
Date: Tue, 20 Aug 2024 10:47:48 +0800
From: Hao Ge <hao.ge@...ux.dev>
To: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
 martin.lau@...ux.dev, eddyz87@...il.com, song@...nel.org,
 yonghong.song@...ux.dev, john.fastabend@...il.com, kpsingh@...nel.org,
 sdf@...ichev.me, haoluo@...gle.com, jolsa@...nel.org, mykolal@...com,
 shuah@...nel.org
Cc: bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org, Hao Ge <gehao@...inos.cn>,
 Dan Carpenter <dan.carpenter@...aro.org>
Subject: Re: [PATCH] selftests/bpf: Fix incorrect parameters in NULL pointer
 checking

Hi

I apologize for the confusion.

  I mistakenly thought that my previous email 
(https://lore.kernel.org/all/20240820023447.29002-1-hao.ge@linux.dev/)

didn't send due to network issues on my computer, so I resent it.

However, it seems that was not the case.

Please kindly disregard this patch as it is identical to the previous one.

I sincerely apologize for wasting everyone's time

On 8/20/24 10:36, Hao Ge wrote:
> From: Hao Ge <gehao@...inos.cn>
>
> Smatch reported the following warning:
>      ./tools/testing/selftests/bpf/testing_helpers.c:455 get_xlated_program()
>      warn: variable dereferenced before check 'buf' (see line 454)
>
> It seems correct,so let's modify it based on it's suggestion.
>
> Actually,commit b23ed4d74c4d ("selftests/bpf: Fix invalid pointer
> check in get_xlated_program()") fixed an issue in the test_verifier.c
> once,but it was reverted this time.
>
> Let's solve this issue with the minimal changes possible.
>
> Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> Closes: https://lore.kernel.org/all/1eb3732f-605a-479d-ba64-cd14250cbf91@stanley.mountain/
> Fixes: b4b7a4099b8c ("selftests/bpf: Factor out get_xlated_program() helper")
> Signed-off-by: Hao Ge <gehao@...inos.cn>
> ---
>   tools/testing/selftests/bpf/testing_helpers.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c
> index d5379a0e6da8..34dfea295c8e 100644
> --- a/tools/testing/selftests/bpf/testing_helpers.c
> +++ b/tools/testing/selftests/bpf/testing_helpers.c
> @@ -451,7 +451,7 @@ int get_xlated_program(int fd_prog, struct bpf_insn **buf, __u32 *cnt)
>   
>   	*cnt = xlated_prog_len / buf_element_size;
>   	*buf = calloc(*cnt, buf_element_size);
> -	if (!buf) {
> +	if (!*buf) {
>   		perror("can't allocate xlated program buffer");
>   		return -ENOMEM;
>   	}
Thanks

Best regards

Hao