YOSHIFUJI Hideaki / 吉藤英明 said the following on 2008-3-31 17:15:

In article [ref] (at Mon, 31 Mar 2008 17:08:38 +0800), Wang Chen [off-list ref] says:

quoted

Check length of setsockopt's optval, which provided by user, before copy it
from user space.

Please use "<" not "==".

There are two reasons that why I only check whether
len of optval is equal to that one in user space.
1. We currently copy the entire structure from user
   to kernel.
2. In other cases, such as IPV6_LEAVE/JOIN_ANYCAST,
   we check whether the len is equal to struct's len.

So, Yoshifuji-san, can you tell me more about why we
should use "<"? :)

--WCN