netdev - RE: natsemi.c ioctl fix or mii register access

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Date:	Thu, 22 May 2008 12:46:13 -0600
From:	<glenn_engel@...lent.com>
To:	<jgarzik@...ox.com>
Cc:	<netdev@...r.kernel.org>
Subject: RE: natsemi.c ioctl fix or mii register access

The core only copies the ifreq struct.  In the case of SIOC[GS]MIIPHY the ifru_data field is a pointer to additional user space information about the ioctl (phy_id, register number).

Thus, an additional copy_from/to_user is required to extract this additional information.  

I suppose this copy could be done in dev.c for these ioctls but it would also need to tweak the ifru_data field to point to local storage before/after the ioctl calls.  Perhaps this was the original intent and was not noticed since ethtool doesn't use these ioctls.  I just assumed the natsemi driver was the odd duck but perhaps none of them work with these ioctls at this point.

--
Glenn

> -----Original Message-----
> From: Jeff Garzik [mailto:jgarzik@...ox.com]
> Sent: Thursday, May 22, 2008 11:05 AM
> To: ENGEL,GLENN (A-Labs,ex1)
> Cc: netdev@...r.kernel.org
> Subject: Re: natsemi.c ioctl fix or mii register access
> 
> glenn_engel@...lent.com wrote:
> > Hi,
> >
> > I recently discovered the ioctl implementation in natsemi.c had a few
> bugs in dealing with the user ioctls to send and receive MII commands
> (SIOCGMIIPHY and SIOCSMIIPHY).
> >
> > The specific problems noted and fixed:
> >
> > 1. The if_mii macro casts it's return to be (struct mii_ioctl_data *)
> but in reality it returns a pointer to the user space pointer (struct
> mii_ioctl_data**).   This looks to be a problem with the mii_macro to
> me.  I changed this to use the ifr_data macro instead.
> >
> > 2. Since the mii_ioctl_data structure resides in user space, it must
> be copied into kernel space before access and copied back for read
> results.  References to the pointer were changed to point to the local
> copy (data-> changed to mii_data.)
> 
> This is completely incorrect.  The copying is done for us inside net
> core.
> 
> 	Jeff
> 
> 
> 


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