fib_trie: leaf_walk_rcu should not compute key if key is less than pn->key

We were computing the child index in cases where the key value we were
looking for was actually less than the base key of the tnode.  As a result
we were getting incorrect index values that would cause us to skip over
some children.

To fix this I have added a test that will force us to use child index 0 if
the key we are looking for is less than the key of the current tnode.

Fixes: 8be33e955cb9 ("fib_trie: Fib walk rcu should take a tnode and key instead of a trie and a leaf")
Reported-by: Brian Rak <brak@gameservers.com>
Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 6c2af797f2f92b93cf4ea28d1d5deee4e725f757..744e5936c10d7ec555d1ca621f5bd4be57f1c72b 100644 (file)
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1569,7 +1569,7 @@ static struct key_vector *leaf_walk_rcu(struct key_vector **tn, t_key key)
        do {
                /* record parent and next child index */
                pn = n;
-               cindex = key ? get_index(key, pn) : 0;
+               cindex = (key > pn->key) ? get_index(key, pn) : 0;
 
                if (cindex >> pn->bits)
                        break;