linux-kernel - Re: [PATCH v2] selftests/seccomp: Improve error logging in get_proc

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Message-ID: <202505280933.33EEDC4DC8@keescook>
Date: Wed, 28 May 2025 09:36:28 -0700
From: Kees Cook <kees@...nel.org>
To: Sameeksha Sankpal <sameekshasankpal@...il.com>
Cc: skhan@...uxfoundation.org, luto@...capital.net, wad@...omium.org,
	shuah@...nel.org, linux-kselftest@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] selftests/seccomp: Improve error logging in
 get_proc_stat()

On Wed, May 28, 2025 at 06:38:39AM +0530, Sameeksha Sankpal wrote:
> Use TH_LOG to report failure when reading /proc/<pid>/stat in
> get_proc_stat(), following kernel test framework conventions.
> 
> Previously, printf() was used which is discouraged.

printf wasn't used previous, that was in your v1. :)

> 
> Suggested-by: Kees Cook <kees@...nel.org>
> 

No blank line here -- other tags should all be together with the S-o-b
line.

> Signed-off-by: Sameeksha Sankpal <sameekshasankpal@...il.com>
> ---
> v1 -> v2:
> - Used TH_LOG instead of printf for error logging
> - Moved variable declaration to the top of the function
> - Applied review suggestion by Kees Cook
> 
>  tools/testing/selftests/seccomp/seccomp_bpf.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
> index d6a85d7b26da..0f12052ef1c7 100644
> --- a/tools/testing/selftests/seccomp/seccomp_bpf.c
> +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
> @@ -4505,14 +4505,14 @@ static char get_proc_stat(struct __test_metadata *_metadata, pid_t pid)
>  	char proc_path[100] = {0};
>  	char status;
>  	char *line;
> +	int rc;
>  
>  	snprintf(proc_path, sizeof(proc_path), "/proc/%d/stat", pid);
>  	ASSERT_EQ(get_nth(_metadata, proc_path, 3, &line), 1);
> -	int rc = get_nth(_metadata, proc_path, 3, &line);
> -    	if (rc != 1) {
> -        	printf("[ERROR] user_notification_fifo: failed to read stat for PID %d (rc=%d)\n", pid, rc);
> -    	}
> -    	ASSERT_EQ(rc, 1);

This patch is against your v1 patch -- it doesn't apply to the seccomp
tree as-is. Please rebase your v2 off of the upstream tree rather than
your v1.

> +	rc = get_nth(_metadata, proc_path, 3, &line);
> +    ASSERT_EQ(rc, 1) {

Indenting looks wrong here, double-check you're using tabs. (And please
use scripts/checkpatch.pl to check your patch for common errors.)

> +		TH_LOG("user_notification_fifo: failed to read stat for PID %d (rc=%d)", pid, rc);
> +	}
>  	status = *line;
>  	free(line);

Code-wise, it looks good. Please respin for a v3 and this change should
be good to land.

-Kees

-- 
Kees Cook