[IPV4] fib_hash: fix duplicated route issue

http://bugzilla.kernel.org/show_bug.cgi?id=9493

The fib allows making identical routes with 'ip route replace'.
This patch makes the fib return -EEXIST if replacement would cause duplication.

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/ipv4/fib_hash.c b/net/ipv4/fib_hash.c
index 527a6e0af5b6..99071d79c5e7 100644
--- a/net/ipv4/fib_hash.c
+++ b/net/ipv4/fib_hash.c
@@ -444,6 +444,9 @@ static int fn_hash_insert(struct fib_table *tb, struct fib_config *cfg)
                         struct fib_info *fi_drop;
                         u8 state;
 
+                        if (fi->fib_treeref > 1)
+                                goto out;
+
                         write_lock_bh(&fib_hash_lock);
                         fi_drop = fa->fa_info;
                         fa->fa_info = fi;