fib: add rtnl locking in ip_fib_net_exit

Daniel J Blueman reported a lockdep splat in trie_firstleaf(), caused by
RTNL being not locked before a call to fib_table_flush()

Reported-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index f116ce8f1b46..451088330bbb 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1068,6 +1068,7 @@ static void ip_fib_net_exit(struct net *net)
         fib4_rules_exit(net);
 #endif
 
+        rtnl_lock();
         for (i = 0; i < FIB_TABLE_HASHSZ; i++) {
                 struct fib_table *tb;
                 struct hlist_head *head;
@@ -1080,6 +1081,7 @@ static void ip_fib_net_exit(struct net *net)
                         fib_free_table(tb);
                 }
         }
+        rtnl_unlock();
         kfree(net->ipv4.fib_table_hash);
 }