linux-kernel - Re: [PATCH] staging: vt6655: preserve address space by not casting

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Date:	Mon, 16 Jun 2014 10:55:56 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Martin Kepplinger <martink@...teo.de>
Cc:	gregkh@...uxfoundation.org, devel@...verdev.osuosl.org,
	forest@...ttletooquiet.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: vt6655: preserve address space by not casting

On Fri, Jun 13, 2014 at 12:11:51PM +0200, Martin Kepplinger wrote:
> Fix the sparse error: cast removes address space of expression.
> ---
> Is that even correct?

It's correct but not complete.

vt6655 impliment their own versions of ethtool_ioctl() when they should
be using the standard versions.

The vt6655 version of ethtool_ioctl() should be annotated so it's marked
that the second parameter is marked as a __user pointer.  It doesn't
print a Sparse warning because at a certain point Sparse just says:
"warning: too many warnings" and gives up.

> I haven't signed-off on it yet.
> ethtool_ioctl() takes a (void *) as user data, dereferenced and assigend to u32.
> applies to next-20140611

It doesn't dereference the pointer.  You are getting mixed up with the
vt6656 version of ethtool_ioctl() I think?  You're not allowed to
dereference __user pointers.

regards,
dan carpenter

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