linux-kernel - Re: [PATCH] Yama: access current->comm directly

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Message-ID: <5016FADD.1030503@canonical.com>
Date:	Mon, 30 Jul 2012 14:21:33 -0700
From:	John Johansen <john.johansen@...onical.com>
To:	Kees Cook <keescook@...omium.org>
CC:	linux-kernel@...r.kernel.org,
	James Morris <james.l.morris@...cle.com>,
	linux-security-module@...r.kernel.org
Subject: Re: [PATCH] Yama: access current->comm directly

On 07/30/2012 09:58 AM, Kees Cook wrote:
> The core ptrace access checking routine already holds the task lock,
> so there is no need to use get_task_comm() which just tries to take the
> lock again. Drop its use and access current->comm directly.
> 
> Reported-by: Fengguang Wu <fengguang.wu@...el.com>
> Suggested-by: Oleg Nesterov <oleg@...hat.com>
> Cc: stable@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.org>
yep, looks good

Acked-by: John Johansen <john.johansen@...onical.com>

> ---
>  security/yama/yama_lsm.c |    6 ++----
>  1 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
> index 83554ee..20a68ca 100644
> --- a/security/yama/yama_lsm.c
> +++ b/security/yama/yama_lsm.c
> @@ -279,12 +279,10 @@ static int yama_ptrace_access_check(struct task_struct *child,
>  	}
>  
>  	if (rc) {
> -		char name[sizeof(current->comm)];
> +		/* task_lock is held by the caller, so use comm directly. */
>  		printk_ratelimited(KERN_NOTICE
>  			"ptrace of pid %d was attempted by: %s (pid %d)\n",
> -			child->pid,
> -			get_task_comm(name, current),
> -			current->pid);
> +			child->pid, current->comm, current->pid);
>  	}
>  
>  	return rc;
> 

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