ipv6 sit: Set relay to 0.0.0.0 directly if relay_prefixlen == 0.

ipv6 sit: Set relay to 0.0.0.0 directly if relay_prefixlen == 0.

Do not use bit-shift if relay_prefixlen == 0;
relay_prefix << 32 does not result in 0.

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

1 files changed, 6 insertions, 3 deletions

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 193d0c6c5ce2..510d31f3cb96 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -1014,9 +1014,12 @@ ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
                                          ip6rd.prefixlen);
                         if (!ipv6_addr_equal(&prefix, &ip6rd.prefix))
                                 goto done;
-                        relay_prefix = ip6rd.relay_prefix &
-                                       htonl(0xffffffffUL <<
-                                             (32 - ip6rd.relay_prefixlen));
+                        if (ip6rd.relay_prefixlen)
+                                relay_prefix = ip6rd.relay_prefix &
+                                               htonl(0xffffffffUL <<
+                                                     (32 - ip6rd.relay_prefixlen));
+                        else
+                                relay_prefix = 0;
                         if (relay_prefix != ip6rd.relay_prefix)
                                 goto done;