linux-kernel - Re: [PATCH] USB: serial: fix invalid user-pointer checks

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Message-ID: <1478689111.2428.6.camel@suse.com>
Date:   Wed, 09 Nov 2016 11:58:31 +0100
From:   Oliver Neukum <oneukum@...e.com>
To:     Johan Hovold <johan@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH] USB: serial: fix invalid user-pointer checks

On Tue, 2016-11-08 at 16:41 +0100, Johan Hovold wrote:
> On Tue, Nov 08, 2016 at 03:13:13PM +0100, Oliver Neukum wrote:
> > On Tue, 2016-11-08 at 13:26 +0100, Johan Hovold wrote:
> > > Drop invalid user-pointer checks from ioctl handlers.
> > > 
> > > A NULL-pointer can be valid in user space and copy_to_user() takes
> > > care
> > > of sanity checking.
> > 
> > Shouldn't we bail out early in these cases?
> 
> I don't think it's worth it, and this is also the general pattern for
> such ioctls. The added overhead for an error case like this is really
> negligible.

OK, as you say.

	Regards
		Oliver