Date:   Mon, 29 Nov 2021 11:01:40 -0500
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Yafang Shao <laoar.shao@gmail.com>
Cc:     akpm@linux-foundation.org, netdev@vger.kernel.org,
        bpf@vger.kernel.org, linux-perf-users@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, oliver.sang@intel.com, lkp@intel.com,
        Kees Cook <keescook@chromium.org>,
        David Hildenbrand <david@redhat.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
        Andrii Nakryiko <andrii.nakryiko@gmail.com>,
        Michal Miroslaw <mirq-linux@rere.qmqm.pl>,
        Peter Zijlstra <peterz@infradead.org>,
        Matthew Wilcox <willy@infradead.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Petr Mladek <pmladek@suse.com>
Subject: Re: [PATCH v2 4/7] fs/binfmt_elf: replace open-coded string copy
 with get_task_comm
Message-ID: <20211129110140.733475f3@gandalf.local.home>
In-Reply-To: <20211120112738.45980-5-laoar.shao@gmail.com>
References: <20211120112738.45980-1-laoar.shao@gmail.com>
        <20211120112738.45980-5-laoar.shao@gmail.com>
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On Sat, 20 Nov 2021 11:27:35 +0000
Yafang Shao <laoar.shao@gmail.com> wrote:

> diff --git a/include/linux/elfcore-compat.h b/include/linux/elfcore-compat.h
> index e272c3d452ce..54feb64e9b5d 100644
> --- a/include/linux/elfcore-compat.h
> +++ b/include/linux/elfcore-compat.h
> @@ -43,6 +43,11 @@ struct compat_elf_prpsinfo
>  	__compat_uid_t			pr_uid;
>  	__compat_gid_t			pr_gid;
>  	compat_pid_t			pr_pid, pr_ppid, pr_pgrp, pr_sid;
> +	/*
> +	 * The hard-coded 16 is derived from TASK_COMM_LEN, but it can't be
> +	 * changed as it is exposed to userspace. We'd better make it hard-coded
> +	 * here.

Didn't I once suggest having a macro called something like:

  TASK_COMM_LEN_16 ?


https://lore.kernel.org/all/20211014221409.5da58a42@oasis.local.home/

-- Steve


> +	 */
>  	char				pr_fname[16];
>  	char				pr_psargs[ELF_PRARGSZ];
>  };
> diff --git a/include/linux/elfcore.h b/include/linux/elfcore.h
> index 957ebec35aad..746e081879a5 100644
> --- a/include/linux/elfcore.h
> +++ b/include/linux/elfcore.h
> @@ -65,6 +65,11 @@ struct elf_prpsinfo
>  	__kernel_gid_t	pr_gid;
>  	pid_t	pr_pid, pr_ppid, pr_pgrp, pr_sid;
>  	/* Lots missing */
> +	/*
> +	 * The hard-coded 16 is derived from TASK_COMM_LEN, but it can't be
> +	 * changed as it is exposed to userspace. We'd better make it hard-coded
> +	 * here.
> +	 */
>  	char	pr_fname[16];	/* filename of executable */
>  	char	pr_psargs[ELF_PRARGSZ];	/* initial part of arg list */
>  };