[IPV6]: Ensure to truncate result and return full length for sticky options.

Bug noticed by Chris Wright <chrisw@sous-sol.org>.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index eceed09e434..1d56b465bdd 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -825,9 +825,9 @@ static int ipv6_getsockopt_sticky(struct sock *sk, struct ipv6_txoptions *opt,
                 return 0;
 
         len = min_t(unsigned 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;
+        return ipv6_optlen(hdr);
 }
 
 static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,