linux-kernel - Re: [PATCH 4/6] proc: disable mem

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Date:	Wed,  9 Mar 2011 14:22:03 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Stephen Wilson <wilsons@...rt.ca>
Cc:	kosaki.motohiro@...fujitsu.com, linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Rik van Riel <riel@...hat.com>,
	Roland McGrath <roland@...hat.com>,
	Matt Mackall <mpm@...enic.com>,
	David Rientjes <rientjes@...gle.com>,
	Nick Piggin <npiggin@...nel.dk>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Mel Gorman <mel@....ul.ie>, Ingo Molnar <mingo@...e.hu>,
	Michel Lespinasse <walken@...gle.com>,
	Hugh Dickins <hughd@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] proc: disable mem_write after exec

> This change makes mem_write() observe the same constraints as mem_read().  This
> is particularly important for mem_write as an accidental leak of the fd across
> an exec could result in arbitrary modification of the target process' memory.
> IOW, /proc/pid/mem is implicitly close-on-exec.
> 
> Signed-off-by: Stephen Wilson <wilsons@...rt.ca>
> ---
>  fs/proc/base.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 9d096e8..e52702d 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -848,6 +848,10 @@ static ssize_t mem_write(struct file * file, const char __user *buf,
>  	if (check_mem_permission(task))
>  		goto out;
>  
> +	copied = -EIO;
> +	if (file->private_data != (void *)((long)current->self_exec_id))
> +		goto out;
> +

I agree.
	Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>



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