Re: [PATCH] lib: introduce strdup_from_user

From: Alexey Dobriyan
Date: Fri Jun 03 2011 - 14:26:25 EST

On Fri, Jun 3, 2011 at 9:22 PM, Timur Tabi <timur@xxxxxxxxxxxxx> 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.

> Besides, it was Alan's idea to make this a common function.  I can easily put it
> back in my driver.

Don't do that.
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