netns: oops in ip[6]_frag_reasm incrementing stats

dev can be NULL in ip[6]_frag_reasm for skb's coming from RAW sockets.

Quagga's OSPFD sends fragmented packets on a RAW socket, when netfilter
conntrack reassembles them on the OUTPUT path you hit this code path.

You can test it with something like "hping2 -0 -d 2000 -f AA.BB.CC.DD"

With help from Jarek Poplawski.
Signed-off-by: Jorge Boncompte [DTI2] <jorge@dti2.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ip_fragment.c

@@ -463,6 +463,7 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
 			 struct net_device *dev)
 {
+	struct net *net = container_of(qp->q.net, struct net, ipv4.frags);
 	struct iphdr *iph;
 	struct sk_buff *fp, *head = qp->q.fragments;
 	int len;
@@ -548,7 +549,7 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
 	iph = ip_hdr(head);
 	iph->frag_off = 0;
 	iph->tot_len = htons(len);
-	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_REASMOKS);
+	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS);
 	qp->q.fragments = NULL;
 	return 0;
 

net/ipv6/reassembly.c

@@ -452,6 +452,7 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 			  struct net_device *dev)
 {
+	struct net *net = container_of(fq->q.net, struct net, ipv6.frags);
 	struct sk_buff *fp, *head = fq->q.fragments;
 	int    payload_len;
 	unsigned int nhoff;
@@ -551,8 +552,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 					  head->csum);
 
 	rcu_read_lock();
-	IP6_INC_STATS_BH(dev_net(dev),
-			 __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
+	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
 	rcu_read_unlock();
 	fq->q.fragments = NULL;
 	return 1;
@@ -566,8 +566,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 		printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
 out_fail:
 	rcu_read_lock();
-	IP6_INC_STATS_BH(dev_net(dev),
-			 __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
+	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 	rcu_read_unlock();
 	return -1;
 }