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From: Bastian Blank <bastian@waldi.eu.org>
To: Pekka J Enberg <penberg@cs.helsinki.fi>
Cc: torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
	stable@kernel.org, jens.axboe@oracle.com,
	akpm@linux-foundation.org, ndenev@gmail.com,
	oliver.pntr@gmail.com
Subject: Re: [PATCH] splice: fix user pointer access in get_iovec_page_array()
Date: Sun, 10 Feb 2008 16:17:35 +0100	[thread overview]
Message-ID: <20080210151735.GA2810@wavehammer.waldi.eu.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0802101644510.12440@sbz-30.cs.Helsinki.FI>

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On Sun, Feb 10, 2008 at 04:47:57PM +0200, Pekka J Enberg wrote:
> From: Bastian Blank <bastian@waldi.eu.org>
> 
> The commit 8811930dc74a503415b35c4a79d14fb0b408a361 ("splice: missing user
> pointer access verification") added access_ok() to copy_from_user_mmap_sem()
> which only ensures we can copy the struct iovecs from userspace to the kernel
> but we also must check whether we can access the actual memory region pointed
> to by the struct iovec to close the local root exploit.
> 
> Cc: <stable@kernel.org>
> Cc: Jens Axboe <jens.axboe@oracle.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Bastian Blank <waldi@debian.org>

> Index: linux-2.6/fs/splice.c
> ===================================================================
> --- linux-2.6.orig/fs/splice.c
> +++ linux-2.6/fs/splice.c
> @@ -1237,6 +1237,9 @@ static int get_iovec_page_array(const st
>  		if (unlikely(!base))
>  			break;
>  
> +		if (unlikely(!access_ok(VERIFY_READ, base, len)))
> +			break;
> +
>  		/*
>  		 * Get this base offset and number of pages, then map
>  		 * in the user pages.

-- 
Those who hate and fight must stop themselves -- otherwise it is not stopped.
		-- Spock, "Day of the Dove", stardate unknown

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  reply	other threads:[~2008-02-10 15:17 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-10 14:47 Pekka J Enberg
2008-02-10 15:17 ` Bastian Blank [this message]
2008-02-10 15:31   ` Oliver Pinter
2008-02-10 23:37 ` Willy Tarreau
2008-02-11  6:24   ` Oliver Pinter
2008-02-11  7:29 ` [PATCH] vmsplice exploit fix (was: splice: fix user pointer access in get_iovec_page_array) Daniel Phillips
2008-02-11  7:49   ` Pekka Enberg
2008-02-11  8:00     ` Daniel Phillips
2008-02-11  7:53   ` [stable] " Greg KH
2008-02-11  8:05     ` Daniel Phillips

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