Revert "blackhole_netdev: fix syzkaller reported issue"

This reverts commit b0818f80c8c1bc215bba276bd61c216014fab23b.

Started seeing weird behavior after this patch especially in
the IPv6 code path. Haven't root caused it, but since this was
applied to net branch, taking a precautionary measure to revert
it and look / analyze those failures

Revert this now and I'll send a better fix after analysing / fixing
the weirdness observed.

CC: Eric Dumazet <edumazet@google.com>
CC: Wei Wang <weiwan@google.com>
CC: David S. Miller <davem@davemloft.net>
Signed-off-by: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 4c87594d1389d6e0927cbfa0ff7b5e631c331e84..34ccef18b40e60e283a63c18102fef8b927cbfaf 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -6996,7 +6996,7 @@ static struct rtnl_af_ops inet6_ops __read_mostly = {
 
 int __init addrconf_init(void)
 {
-       struct inet6_dev *idev, *bdev;
+       struct inet6_dev *idev;
        int i, err;
 
        err = ipv6_addr_label_init();
@@ -7036,14 +7036,10 @@ int __init addrconf_init(void)
         */
        rtnl_lock();
        idev = ipv6_add_dev(init_net.loopback_dev);
-       bdev = ipv6_add_dev(blackhole_netdev);
        rtnl_unlock();
        if (IS_ERR(idev)) {
                err = PTR_ERR(idev);
                goto errlo;
-       } else if (IS_ERR(bdev)) {
-               err = PTR_ERR(bdev);
-               goto errlo;
        }
 
        ip6_route_init_special_entries();
@@ -7128,7 +7124,6 @@ void addrconf_cleanup(void)
                addrconf_ifdown(dev, 1);
        }
        addrconf_ifdown(init_net.loopback_dev, 2);
-       addrconf_ifdown(blackhole_netdev, 2);
 
        /*
         *      Check hash table.

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 7421207288690078f021117980a28fd01c3a4255..a63ff85fe14198fc23a5cbc7abcd107df5df00c8 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -155,9 +155,10 @@ void rt6_uncached_list_del(struct rt6_info *rt)
 
 static void rt6_uncached_list_flush_dev(struct net *net, struct net_device *dev)
 {
+       struct net_device *loopback_dev = net->loopback_dev;
        int cpu;
 
-       if (dev == net->loopback_dev)
+       if (dev == loopback_dev)
                return;
 
        for_each_possible_cpu(cpu) {
@@ -170,7 +171,7 @@ static void rt6_uncached_list_flush_dev(struct net *net, struct net_device *dev)
                        struct net_device *rt_dev = rt->dst.dev;
 
                        if (rt_idev->dev == dev) {
-                               rt->rt6i_idev = in6_dev_get(blackhole_netdev);
+                               rt->rt6i_idev = in6_dev_get(loopback_dev);
                                in6_dev_put(rt_idev);
                        }
 
@@ -385,11 +386,13 @@ static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 {
        struct rt6_info *rt = (struct rt6_info *)dst;
        struct inet6_dev *idev = rt->rt6i_idev;
+       struct net_device *loopback_dev =
+               dev_net(dev)->loopback_dev;
 
-       if (idev && idev->dev != dev_net(dev)->loopback_dev) {
-               struct inet6_dev *ibdev = in6_dev_get(blackhole_netdev);
-               if (ibdev) {
-                       rt->rt6i_idev = ibdev;
+       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);
                }
        }