From 17ecf590b3cba19d9ecb410e340aa78128382abb Mon Sep 17 00:00:00 2001 From: Wei Wang Date: Fri, 6 Oct 2017 12:06:09 -0700 Subject: ipv6: add key length check into rt6_select() After rwlock is replaced with rcu and spinlock, fib6_lookup() could potentially return an intermediate node if other thread is doing fib6_del() on a route which is the only route on the node so that fib6_repair_tree() will be called on this node and potentially assigns fn->leaf to the its child's fn->leaf. In order to detect this situation in rt6_select(), we have to check if fn->fn_bit is consistent with the key length stored in the route. And depending on if the fn is in the subtree or not, the key is either rt->rt6i_dst or rt->rt6i_src. If any inconsistency is found, that means the node no longer holds valid routes in it. So net->ipv6.ip6_null_entry is returned. Signed-off-by: Wei Wang Signed-off-by: Martin KaFai Lau Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv6/route.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'net/ipv6') diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 05dc450af441..24b80f43bbfb 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -755,6 +755,7 @@ static struct rt6_info *rt6_select(struct net *net, struct fib6_node *fn, struct rt6_info *leaf = fn->leaf; struct rt6_info *match, *rt0; bool do_rr = false; + int key_plen; if (!leaf) return net->ipv6.ip6_null_entry; @@ -763,6 +764,19 @@ static struct rt6_info *rt6_select(struct net *net, struct fib6_node *fn, if (!rt0) fn->rr_ptr = rt0 = leaf; + /* Double check to make sure fn is not an intermediate node + * and fn->leaf does not points to its child's leaf + * (This might happen if all routes under fn are deleted from + * the tree and fib6_repair_tree() is called on the node.) + */ + key_plen = rt0->rt6i_dst.plen; +#ifdef CONFIG_IPV6_SUBTREES + if (rt0->rt6i_src.plen) + key_plen = rt0->rt6i_src.plen; +#endif + if (fn->fn_bit != key_plen) + return net->ipv6.ip6_null_entry; + match = find_rr_leaf(fn, leaf, rt0, rt0->rt6i_metric, oif, strict, &do_rr); -- cgit v1.2.3