IB: Fix RCU lockdep splats

Commit f2c31e32b37 ("net: fix NULL dereferences in check_peer_redir()")
forgot to take care of infiniband uses of dst neighbours.

Many thanks to Marc Aurele who provided a nice bug report and feedback.

Reported-by: Marc Aurele La France <tsi@ualberta.ca>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>
Cc: <stable@kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/infiniband/core/addr.c b/drivers/infiniband/core/addr.c
index 691276bafd78..e9cf51b1343b 100644
--- a/drivers/infiniband/core/addr.c
+++ b/drivers/infiniband/core/addr.c
@@ -216,7 +216,9 @@ static int addr4_resolve(struct sockaddr_in *src_in,
 
         neigh = neigh_lookup(&arp_tbl, &rt->rt_gateway, rt->dst.dev);
         if (!neigh || !(neigh->nud_state & NUD_VALID)) {
+                rcu_read_lock();
                 neigh_event_send(dst_get_neighbour(&rt->dst), NULL);
+                rcu_read_unlock();
                 ret = -ENODATA;
                 if (neigh)
                         goto release;
@@ -274,15 +276,16 @@ static int addr6_resolve(struct sockaddr_in6 *src_in,
                 goto put;
         }
 
+        rcu_read_lock();
         neigh = dst_get_neighbour(dst);
         if (!neigh || !(neigh->nud_state & NUD_VALID)) {
                 if (neigh)
                         neigh_event_send(neigh, NULL);
                 ret = -ENODATA;
-                goto put;
+        } else {
+                ret = rdma_copy_addr(addr, dst->dev, neigh->ha);
         }
-
-        ret = rdma_copy_addr(addr, dst->dev, neigh->ha);
+        rcu_read_unlock();
 put:
         dst_release(dst);
         return ret;