re: ipvs: Pull out crosses_local_route_boundary logic

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Alex Gartrell,

This is a semi-automatic email about new static checker warnings.

The patch 4a4739d56b00: "ipvs: Pull out crosses_local_route_boundary
logic" from Sep 9, 2014, leads to the following Smatch complaint:

net/netfilter/ipvs/ip_vs_xmit.c:318 __ip_vs_get_out_rt()
	 error: we previously assumed 'dest' could be null (see line 312)

net/netfilter/ipvs/ip_vs_xmit.c
   270          if (dest) {
                    ^^^^
Old check.

   271                  dest_dst = __ip_vs_dst_check(dest);
   272                  if (likely(dest_dst))
   273                          rt = (struct rtable *) dest_dst->dst_cache;
   274                  else {
   275                          dest_dst = ip_vs_dest_dst_alloc();
   276                          spin_lock_bh(&dest->dst_lock);
   277                          if (!dest_dst) {
   278                                  __ip_vs_dst_set(dest, NULL, NULL, 0);
   279                                  spin_unlock_bh(&dest->dst_lock);
   280                                  goto err_unreach;
   281                          }
   282                          rt = do_output_route4(net, dest->addr.ip, rt_mode,
   283                                                &dest_dst->dst_saddr.ip);
   284                          if (!rt) {
   285                                  __ip_vs_dst_set(dest, NULL, NULL, 0);
   286                                  spin_unlock_bh(&dest->dst_lock);
   287                                  ip_vs_dest_dst_free(dest_dst);
   288                                  goto err_unreach;
   289                          }
   290                          __ip_vs_dst_set(dest, dest_dst, &rt->dst, 0);
   291                          spin_unlock_bh(&dest->dst_lock);
   292                          IP_VS_DBG(10, "new dst %pI4, src %pI4, refcnt=%d\n",
   293                                    &dest->addr.ip, &dest_dst->dst_saddr.ip,
   294                                    atomic_read(&rt->dst.__refcnt));
   295                  }
   296                  daddr = dest->addr.ip;
   297                  if (ret_saddr)
   298                          *ret_saddr = dest_dst->dst_saddr.ip;
   299          } else {
   300                  __be32 saddr = htonl(INADDR_ANY);
   301  
   302                  noref = 0;
   303  
   304                  /* For such unconfigured boxes avoid many route lookups
   305                   * for performance reasons because we do not remember saddr
   306                   */
   307                  rt_mode &= ~IP_VS_RT_MODE_CONNECT;
   308                  rt = do_output_route4(net, daddr, rt_mode, &saddr);
   309                  if (!rt)
   310                          goto err_unreach;
   311			if (ret_saddr)
   312				*ret_saddr = saddr;
   313		}
   314	
   315		local = (rt->rt_flags & RTCF_LOCAL) ? 1 : 0;
   316		if (unlikely(crosses_local_route_boundary(skb_af, skb, rt_mode,
   317							  local))) {
   318			IP_VS_DBG_RL("We are crossing local and non-local addresses"
   319				     " daddr=%pI4\n", &dest->addr.ip);
                                                       ^^^^^^^^^^^^^
New unchecked dereference.

   320			goto err_put;

Also:
net/netfilter/ipvs/ip_vs_xmit.c:460 __ip_vs_get_out_rt_v6() error: we previously assumed 'dest' could be null (see line 415)

regards,
dan carpenter