Date: Fri, 3 Jun 2011 13:37:26 -0500
From: Scott Wood <scottwood@freescale.com>
To: Alexey Dobriyan <adobriyan@gmail.com>
CC: Timur Tabi <timur@freescale.com>, <alan@lxorguk.ukuu.org.uk>,
        <linux-kernel@vger.kernel.org>, <akpm@linux-foundation.org>
Subject: Re: [PATCH] lib: introduce strdup_from_user
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On Fri, 3 Jun 2011 21:26:21 +0300
Alexey Dobriyan <adobriyan@gmail.com> wrote:

> On Fri, Jun 3, 2011 at 9:22 PM, Timur Tabi <timur@freescale.com> wrote:
> > Alexey Dobriyan wrote:
> >> NAK
> >> It accesses userspace data twice.
> >
> > What's wrong with that?
> 
> If mm is shared, data can or will change under you.
>
> > How else is it supposed to know how much to allocate
> > without using strlen first?
> 
> I don't know.
> What I know is that your function doesn't guarantee NUL-termination.

If the only issue is NUL-termination (and I think that's the only issue,
everything else is userspace shooting itself in the foot), just stick
"str[len] = 0" at the end.

-Scott

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