[NETLINK]: Fix processing of fib_lookup netlink messages

The receive path for fib_lookup netlink messages is lacking sanity
checks for header and payload and is thus vulnerable to malformed
netlink messages causing illegal memory references.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 882f88f..19b1b98 100644 (file)
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -544,12 +544,16 @@ static void nl_fib_input(struct sock *sk, int len)
        struct sk_buff *skb = NULL;
         struct nlmsghdr *nlh = NULL;
        struct fib_result_nl *frn;
-       int err;
        u32 pid;     
        struct fib_table *tb;
        
-       skb = skb_recv_datagram(sk, 0, 0, &err);
+       skb = skb_dequeue(&sk->sk_receive_queue);
        nlh = (struct nlmsghdr *)skb->data;
+       if (skb->len < NLMSG_SPACE(0) || skb->len < nlh->nlmsg_len ||
+           nlh->nlmsg_len < NLMSG_LENGTH(sizeof(*frn))) {
+               kfree_skb(skb);
+               return;
+       }
        
        frn = (struct fib_result_nl *) NLMSG_DATA(nlh);
        tb = fib_get_table(frn->tb_id_in);