[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>

1 files changed, 6 insertions, 2 deletions

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 882f88f6d13..19b1b984d68 100644
--- 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);