vlan: fix a race in egress prio management (3e3aac49) · Commits · 戴 / test

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:

Eric Dumazet <edumazet@google.com> Cc: Patrick McHardy <kaber@trash.net> Signed-off-by:

David S. Miller <davem@davemloft.net>

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++;

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