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authorEric Dumazet <eric.dumazet@gmail.com>2010-03-18 21:16:45 -0700
committerDavid S. Miller <davem@davemloft.net>2010-03-18 21:16:45 -0700
commit0641e4fbf2f824faee00ea74c459a088d94905fd (patch)
tree54fdd8bc2e3a928ff0f7621c06e1e604eaf0529c
parent54d259d474e1fee6f6bb8f0f1360d85195199ac5 (diff)
net: Potential null skb->dev dereference
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>
-rw-r--r--include/linux/netdevice.h8
-rw-r--r--net/8021q/vlan_core.c4
-rw-r--r--net/core/dev.c8
3 files changed, 11 insertions, 9 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c79a88be7c3..fa8b4763799 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -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;
diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
index c0316e0ca6e..c584a0af77d 100644
--- a/net/8021q/vlan_core.c
+++ b/net/8021q/vlan_core.c
@@ -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;
diff --git a/net/core/dev.c b/net/core/dev.c
index bcc490cc945..59d4394d2ce 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -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++;