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Commit 3e3aac49 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

vlan: fix a race in egress prio management 



egress_priority_map[] hash table updates are protected by rtnl,
and we never remove elements until device is dismantled.

We have to make sure that before inserting an new element in hash table,
all its fields are committed to memory or else another cpu could
find corrupt values and crash.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d4b812de

net/8021q/vlan_dev.c

+7 −0
Original line number Diff line number Diff line
@@ -73,6 +73,8 @@ vlan_dev_get_egress_qos_mask(struct net_device *dev, struct sk_buff *skb) 
{

	struct vlan_priority_tci_mapping *mp;



	smp_rmb(); /* coupled with smp_wmb() in vlan_dev_set_egress_priority() */



	mp = vlan_dev_priv(dev)->egress_priority_map[(skb->priority & 0xF)];

	while (mp) {

		if (mp->priority == skb->priority) {
@@ -249,6 +251,11 @@ int vlan_dev_set_egress_priority(const struct net_device *dev, 
	np->next = mp;

	np->priority = skb_prio;

	np->vlan_qos = vlan_qos;

	/* Before inserting this element in hash table, make sure all its fields

	 * are committed to memory.

	 * coupled with smp_rmb() in vlan_dev_get_egress_qos_mask()

	 */

	smp_wmb();

	vlan->egress_priority_map[skb_prio & 0xF] = np;

	if (vlan_qos)

		vlan->nr_egress_mappings++;