Subject: Re: [PATCH]IPv6:remove duplicate check of optlen when setsockopt with IPV6_PKTINFO option

From: Yang Hongyang <[email-masked]>
Date: Thu, 15 Jan 2009 13:25:22 +0800

Herbert Xu wrote:
> On Thu, Jan 15, 2009 at 04:04:49PM +1100, Herbert Xu wrote:
>> On Wed, Jan 14, 2009 at 09:02:42PM -0800, David Miller wrote:
>>> Actually, we return EINVAL just a few lines above this code
>>> block for some other socket option cases when optval==NULL.
>> Well the very next option IPV6_2292PKTOPTIONS returns EFAULT
>> by virtue of not explicitly checking optval == NULL :)
> 
> In fact checking for a NULL pointer is strictly speaking wrong
> since NULL may actually have been mapped in user-space :)

But there are some cases that user-space passes a NULL pointer
to the kernel,Otherwise,copy_from_user needn't to cheak the
NULL pointer either.:)

By the way,I think most part of the ipv6 socket option implementation
are kind of ugly:)

> Cheers,

-- 
Regards
Yang Hongyang