ipv6: release rt6->rt6i_idev properly during ifdown

When a dst is created by addrconf_dst_alloc() for a host route or an
anycast route, dst->dev points to loopback dev while rt6->rt6i_idev
points to a real device.
When the real device goes down, the current cleanup code only checks for
dst->dev and assumes rt6->rt6i_idev->dev is the same. This causes the
refcount leak on the real device in the above situation.
This patch makes sure to always release the refcount taken on
rt6->rt6i_idev during dst_dev_put().

Fixes: 587fea741134 ("ipv6: mark DST_NOGC and remove the operation of
dst_free()")
Reported-by: John Stultz <john.stultz@linaro.org>
Tested-by: John Stultz <john.stultz@linaro.org>
Tested-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index a640fbcba15dbf246e419d3e03da8eca0fa6901a..99d4727f2b186348cacb4e9a9004e1625671ac5c 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -417,14 +417,11 @@ static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
        struct net_device *loopback_dev =
                dev_net(dev)->loopback_dev;
 
-       if (dev != loopback_dev) {
-               if (idev && idev->dev == dev) {
-                       struct inet6_dev *loopback_idev =
-                               in6_dev_get(loopback_dev);
-                       if (loopback_idev) {
-                               rt->rt6i_idev = loopback_idev;
-                               in6_dev_put(idev);
-                       }
+       if (idev && idev->dev != loopback_dev) {
+               struct inet6_dev *loopback_idev = in6_dev_get(loopback_dev);
+               if (loopback_idev) {
+                       rt->rt6i_idev = loopback_idev;
+                       in6_dev_put(idev);
                }
        }
 }