linux-kernel - Re: [PATCH] sparc: copy_from_user() should not return -EFAULT

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Message-ID: <87skakbgy1.fsf@basil.nowhere.org>
Date:	Tue, 05 Jan 2010 18:27:18 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Heiko Carstens <heiko.carstens@...ibm.com>
Cc:	Arjan van de Ven <arjan@...radead.org>,
	Arnd Bergmann <arnd@...db.de>, Ingo Molnar <mingo@...e.hu>,
	David Miller <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sparc: copy_from_user() should not return -EFAULT

Heiko Carstens <heiko.carstens@...ibm.com> writes:

> Subject: [PATCH] sparc: copy_from_user() should not return -EFAULT
>
> From: Heiko Carstens <heiko.carstens@...ibm.com>
>
> Callers of copy_from_user() expect it to return the number of bytes
> it could not copy. In no case it is supposed to return -EFAULT.
>
> In case of a detected buffer overflow just return the requested
> length. In addition one could think of a memset that would clear
> the size of the target object.

Ouch! I would expect this is likely exploitable, e.g. in mount

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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