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net: Potential null skb->dev dereference

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When doing "ifenslave -d bond0 eth0", there is chance to get NULL
dereference in netif_receive_skb(), because dev->master suddenly becomes
NULL after we tested it.

We should use ACCESS_ONCE() to avoid this (or rcu_dereference())

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-03-18 21:16:45 -07:00 committed by David S. Miller
parent 54d259d474
commit 0641e4fbf2
3 changed files with 11 additions and 9 deletions
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8
include/linux/netdevice.h
View File

@ -2059,12 +2059,12 @@ static inline void skb_bond_set_mac_by_master(struct sk_buff *skb,
* duplicates except for 802.3ad ETH_P_SLOW, alb non-mcast/bcast, and
* ARP on active-backup slaves with arp_validate enabled.
*/
static inline int skb_bond_should_drop(struct sk_buff *skb)
static inline int skb_bond_should_drop(struct sk_buff *skb,
struct net_device *master)
{
struct net_device *dev = skb->dev;
struct net_device *master = dev->master;
if (master) {
struct net_device *dev = skb->dev;
if (master->priv_flags & IFF_MASTER_ARPMON)
dev->last_rx = jiffies;

4
net/8021q/vlan_core.c
View File

@ -11,7 +11,7 @@ int __vlan_hwaccel_rx(struct sk_buff *skb, struct vlan_group *grp,
if (netpoll_rx(skb))
return NET_RX_DROP;
if (skb_bond_should_drop(skb))
if (skb_bond_should_drop(skb, ACCESS_ONCE(skb->dev->master)))
goto drop;
skb->skb_iif = skb->dev->ifindex;
@ -83,7 +83,7 @@ vlan_gro_common(struct napi_struct *napi, struct vlan_group *grp,
{
struct sk_buff *p;
if (skb_bond_should_drop(skb))
if (skb_bond_should_drop(skb, ACCESS_ONCE(skb->dev->master)))
goto drop;
skb->skb_iif = skb->dev->ifindex;

8
net/core/dev.c
View File

@ -2483,6 +2483,7 @@ int netif_receive_skb(struct sk_buff *skb)
{
struct packet_type *ptype, *pt_prev;
struct net_device *orig_dev;
struct net_device *master;
struct net_device *null_or_orig;
struct net_device *null_or_bond;
int ret = NET_RX_DROP;
@ -2503,11 +2504,12 @@ int netif_receive_skb(struct sk_buff *skb)
null_or_orig = NULL;
orig_dev = skb->dev;
if (orig_dev->master) {
if (skb_bond_should_drop(skb))
master = ACCESS_ONCE(orig_dev->master);
if (master) {
if (skb_bond_should_drop(skb, master))
null_or_orig = orig_dev; /* deliver only exact match */
else
skb->dev = orig_dev->master;
skb->dev = master;
}
__get_cpu_var(netdev_rx_stat).total++;