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>

1 files changed, 3 insertions, 3 deletions

diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
index 28a736f3442f..2391b24e8251 100644
--- 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)