[PPPOE]: Use ifindex instead of device pointer in key lookups.

Otherwise we can potentially try to dereference a NULL device
pointer in some cases.
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/pppoe.c

@@ -140,7 +140,7 @@ static struct pppox_sock *__get_item(unsigned long sid, unsigned char *addr, int
 
 	ret = item_hash_table[hash];
 
-	while (ret && !(cmp_addr(&ret->pppoe_pa, sid, addr) && ret->pppoe_dev->ifindex == ifindex))
+	while (ret && !(cmp_addr(&ret->pppoe_pa, sid, addr) && ret->pppoe_ifindex == ifindex))
 		ret = ret->next;
 
 	return ret;
@@ -153,7 +153,7 @@ static int __set_item(struct pppox_sock *po)
 
 	ret = item_hash_table[hash];
 	while (ret) {
-		if (cmp_2_addr(&ret->pppoe_pa, &po->pppoe_pa) && ret->pppoe_dev->ifindex == po->pppoe_dev->ifindex)
+		if (cmp_2_addr(&ret->pppoe_pa, &po->pppoe_pa) && ret->pppoe_ifindex == po->pppoe_ifindex)
 			return -EALREADY;
 
 		ret = ret->next;
@@ -174,7 +174,7 @@ static struct pppox_sock *__delete_item(unsigned long sid, char *addr, int ifind
 	src = &item_hash_table[hash];
 
 	while (ret) {
-		if (cmp_addr(&ret->pppoe_pa, sid, addr) && ret->pppoe_dev->ifindex == ifindex) {
+		if (cmp_addr(&ret->pppoe_pa, sid, addr) && ret->pppoe_ifindex == ifindex) {
 			*src = ret->next;
 			break;
 		}
@@ -529,7 +529,7 @@ static int pppoe_release(struct socket *sock)
 
 	po = pppox_sk(sk);
 	if (po->pppoe_pa.sid) {
-		delete_item(po->pppoe_pa.sid, po->pppoe_pa.remote, po->pppoe_dev->ifindex);
+		delete_item(po->pppoe_pa.sid, po->pppoe_pa.remote, po->pppoe_ifindex);
 	}
 
 	if (po->pppoe_dev)
@@ -577,7 +577,7 @@ static int pppoe_connect(struct socket *sock, struct sockaddr *uservaddr,
 		pppox_unbind_sock(sk);
 
 		/* Delete the old binding */
-		delete_item(po->pppoe_pa.sid,po->pppoe_pa.remote,po->pppoe_dev->ifindex);
+		delete_item(po->pppoe_pa.sid,po->pppoe_pa.remote,po->pppoe_ifindex);
 
 		if(po->pppoe_dev)
 			dev_put(po->pppoe_dev);
@@ -597,6 +597,7 @@ static int pppoe_connect(struct socket *sock, struct sockaddr *uservaddr,
 			goto end;
 
 		po->pppoe_dev = dev;
+		po->pppoe_ifindex = dev->ifindex;
 
 		if (!(dev->flags & IFF_UP))
 			goto err_put;

include/linux/if_pppox.h

@@ -114,6 +114,7 @@ struct pppoe_hdr {
 #ifdef __KERNEL__
 struct pppoe_opt {
 	struct net_device      *dev;	  /* device associated with socket*/
+	int			ifindex;  /* ifindex of device associated with socket */
 	struct pppoe_addr	pa;	  /* what this socket is bound to*/
 	struct sockaddr_pppox	relay;	  /* what socket data will be
 					     relayed to (PPPoE relaying) */
@@ -132,6 +133,7 @@ struct pppox_sock {
 	unsigned short		num;
 };
 #define pppoe_dev	proto.pppoe.dev
+#define pppoe_ifindex	proto.pppoe.ifindex
 #define pppoe_pa	proto.pppoe.pa
 #define pppoe_relay	proto.pppoe.relay