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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
Date: Fri, 3 Jun 2011 13:37:26 -0500	[thread overview]
Message-ID: <20110603133726.0e55d27e@schlenkerla.am.freescale.net> (raw)
In-Reply-To: <BANLkTimB2UanZA4wf=uBGcj=wKmDhCco=w@mail.gmail.com>

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


  parent reply	other threads:[~2011-06-03 18:37 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-06-03 16:45 [PATCH] lib: introduce strdup_from_user Timur Tabi
2011-06-03 17:45 ` Alexey Dobriyan
2011-06-03 18:22   ` Timur Tabi
2011-06-03 18:26     ` Alexey Dobriyan
2011-06-03 18:34       ` Timur Tabi
2011-06-03 18:39         ` Alexey Dobriyan
2011-06-03 18:41           ` Timur Tabi
2011-06-03 18:47             ` Alexey Dobriyan
2011-06-03 18:54               ` Timur Tabi
2011-06-03 18:53           ` Scott Wood
2011-06-03 18:57             ` Timur Tabi
2011-06-03 19:12             ` Alexey Dobriyan
2011-06-03 19:31               ` Scott Wood
2011-06-03 22:41               ` Al Viro
2011-06-03 18:37       ` Scott Wood [this message]
2011-06-03 21:58   ` Alan Cox

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