IPV6: make ipv6_getsockopt_sticky honor user's buffer size

[Chris Wright <chrisw@sous-sol.org>]

Make sure not to copy_to_user more than user's buffer can handle (we
already checked the min, just use it) in ipv6_getsockopt_sticky.  And
while there, minor whitespace cleanup now that ipv6_getsockopt_sticky
call can nicely fit on one line.

Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---

diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 4e0561a..9396551 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -805,7 +805,7 @@ static int ipv6_getsockopt_sticky(struct sock *sk, struct ipv6_txoptions *opt,
 	hdr = opt->hopopt;
 
 	len = min_t(int, len, ipv6_optlen(hdr));
-	if (copy_to_user(optval, hdr, ipv6_optlen(hdr)))
+	if (copy_to_user(optval, hdr, len))
 		return -EFAULT;
 	return len;
 }
@@ -944,8 +944,7 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
 	{
 
 		lock_sock(sk);
-		len = ipv6_getsockopt_sticky(sk, np->opt,
-					     optval, len);
+		len = ipv6_getsockopt_sticky(sk, np->opt, optval, len);
 		release_sock(sk);
 		return put_user(len, optlen);
 	}