ip: ip_options_compile() resilient to NULL skb route

Scot Doyle demonstrated ip_options_compile() could be called with an skb
without an attached route, using a setup involving a bridge, netfilter,
and forged IP packets.

Let's make ip_options_compile() and ip_options_rcv_srr() a bit more
robust, instead of changing bridge/netfilter code.

With help from Hiroaki SHIMODA.

Reported-by: Scot Doyle <lkml@scotdoyle.com>
Tested-by: Scot Doyle <lkml@scotdoyle.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Hiroaki SHIMODA <shimoda.hiroaki@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
index 28a736f3442f456c1abd7b7d56eb2e9c4ffdb493..2391b24e8251e62e2c71eadad172a673a1e76c2f 100644 (file)
--- a/net/ipv4/ip_options.c
+++ b/net/ipv4/ip_options.c
@@ -329,7 +329,7 @@ int ip_options_compile(struct net *net,
                                        pp_ptr = optptr + 2;
                                        goto error;
                                }
-                               if (skb) {
+                               if (rt) {
                                        memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
                                        opt->is_changed = 1;
                                }
@@ -371,7 +371,7 @@ int ip_options_compile(struct net *net,
                                                goto error;
                                        }
                                        opt->ts = optptr - iph;
-                                       if (skb) {
+                                       if (rt)  {
                                                memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
                                                timeptr = (__be32*)&optptr[optptr[2]+3];
                                        }
@@ -603,7 +603,7 @@ int ip_options_rcv_srr(struct sk_buff *skb)
        unsigned long orefdst;
        int err;
 
-       if (!opt->srr)
+       if (!opt->srr || !rt)
                return 0;
 
        if (skb->pkt_type != PACKET_HOST)