xfrm6: ensure to use the same dev when building a bundle

When building a bundle, we set dst.dev and rt6.rt6i_idev.
We must ensure to set the same device for both fields.
Signed-off-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/xfrm6_policy.c

@@ -124,7 +124,7 @@ static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
 	xdst->u.dst.dev = dev;
 	dev_hold(dev);
 
-	xdst->u.rt6.rt6i_idev = in6_dev_get(rt->u.dst.dev);
+	xdst->u.rt6.rt6i_idev = in6_dev_get(dev);
 	if (!xdst->u.rt6.rt6i_idev)
 		return -ENODEV;