linux-kernel - Re: [PATCH 2/2] vsprintf: Add support for userspace strings

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Message-ID: <554FBE06.1010700@nod.at>
Date:	Sun, 10 May 2015 22:22:30 +0200
From:	Richard Weinberger <richard@....at>
To:	Joe Perches <joe@...ches.com>
CC:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] vsprintf: Add support for userspace strings

Am 10.05.2015 um 22:16 schrieb Joe Perches:
> On Sun, 2015-05-10 at 22:11 +0200, Richard Weinberger wrote:
>> Am 10.05.2015 um 22:09 schrieb Joe Perches:
>>> On Sun, 2015-05-10 at 21:42 +0200, Richard Weinberger wrote:
>>>> Add %pL format string to print userspace strings.
>>>> It works like %s but does copy_from_user() instead
>>>> of a memcpy().
>>>
>>> I think this would be much simpler in a new
>>> function rather than complicating string()
>>
>> -ENOPATCH.
> 
> It's your patch, I'm just commenting on it.

Yeah, if you read string() you'll notice that it adds only
very few lines. Duplicating string() is not a good idea.
%pL is not a completely new feature it just covers a %s corner
case.

> I'm not sure there's much value in it.

Maybe because you're not in the kernel-debugging-business? ;-)

> Can it can add security holes if used with %pV?

If abused every kernel function can be used to add security holes.
As I wrote the goal of %pL is for debugging.

Thanks,
//richard
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