linux-kernel - Re: [PATCH] drm/i915: clarify reasoning for the access

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Message-ID: <CAGXu5j+v9ma5rwhtPqtJKzve5q5G_m9VQkAUqJ38VnDFPpvGYw@mail.gmail.com>
Date:	Mon, 11 Mar 2013 14:04:51 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Chris Wilson <chris@...is-wilson.co.uk>,
	Kees Cook <keescook@...omium.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	David Airlie <airlied@...ux.ie>,
	dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm/i915: clarify reasoning for the access_ok call

On Mon, Mar 11, 2013 at 1:51 PM, Chris Wilson <chris@...is-wilson.co.uk> wrote:
> On Mon, Mar 11, 2013 at 12:26:30PM -0700, Kees Cook wrote:
>> This clarifies the comment above the access_ok check so a missing
>> VERIFY_READ doesn't alarm anyone.
>
> Do we really need to copy the interface documentation?
>
> /**
>  * access_ok: - Checks if a user space pointer is valid
>  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
>  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
>  *        to write to a block, it is always safe to read from it.
>  * @addr: User space pointer to start of block to check
>  * @size: Size of block to check
>  */
> -Chris

Probably not. It just seemed like the existing comment was
insufficient after the removal of the redundant VERIFY_READ check that
happened recently.

-Kees

-- 
Kees Cook
Chrome OS Security
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