Re: [PATCH] drm/i915: clarify reasoning for the access_ok call

From: Kees Cook
Date: Mon Mar 11 2013 - 17:04:55 EST

On Mon, Mar 11, 2013 at 1:51 PM, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> 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 Cook
Chrome OS Security
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