8021q: delete cleared egress QoS mappings

vlan_dev_set_egress_priority() currently keeps cleared egress
priority mappings in the hash as tombstones. Repeated set/clear cycles
with distinct skb priorities therefore accumulate mapping nodes until
device teardown and leak memory.

Delete mappings when vlan_prio is cleared instead of keeping tombstones.
Now that the egress mapping lists are RCU protected, the node can be
unlinked safely and freed after a grace period.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@kernel.org
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Co-developed-by: Yuan Tan <yuantan098@gmail.com>
Signed-off-by: Yuan Tan <yuantan098@gmail.com>
Signed-off-by: Longxuan Yu <ylong030@ucr.edu>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Link: https://patch.msgid.link/ecfa6f6ce2467a42647ff4c5221238ae85b79a59.1776647968.git.yuantan098@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index a5340932b657a6a040005664db8063ffa850976a..7aa3af8b10ead0384bbb2e767883b63a37be5fa2 100644 (file)
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -172,26 +172,34 @@ int vlan_dev_set_egress_priority(const struct net_device *dev,
                                 u32 skb_prio, u16 vlan_prio)
 {
        struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
+       struct vlan_priority_tci_mapping __rcu **mpp;
        struct vlan_priority_tci_mapping *mp;
        struct vlan_priority_tci_mapping *np;
        u32 bucket = skb_prio & 0xF;
        u32 vlan_qos = (vlan_prio << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK;
 
        /* See if a priority mapping exists.. */
-       mp = rtnl_dereference(vlan->egress_priority_map[bucket]);
+       mpp = &vlan->egress_priority_map[bucket];
+       mp = rtnl_dereference(*mpp);
        while (mp) {
                if (mp->priority == skb_prio) {
-                       if (mp->vlan_qos && !vlan_qos)
+                       if (!vlan_qos) {
+                               rcu_assign_pointer(*mpp, rtnl_dereference(mp->next));
                                vlan->nr_egress_mappings--;
-                       else if (!mp->vlan_qos && vlan_qos)
-                               vlan->nr_egress_mappings++;
-                       WRITE_ONCE(mp->vlan_qos, vlan_qos);
+                               kfree_rcu(mp, rcu);
+                       } else {
+                               WRITE_ONCE(mp->vlan_qos, vlan_qos);
+                       }
                        return 0;
                }
-               mp = rtnl_dereference(mp->next);
+               mpp = &mp->next;
+               mp = rtnl_dereference(*mpp);
        }
 
        /* Create a new mapping then. */
+       if (!vlan_qos)
+               return 0;
+
        np = kmalloc_obj(struct vlan_priority_tci_mapping);
        if (!np)
                return -ENOBUFS;

diff --git a/net/8021q/vlan_netlink.c b/net/8021q/vlan_netlink.c
index a5b16833e2ceeb204e6602649aa457f2560dbf94..368d53ca7d870998d4ce12bb9a48f946fedcb8ee 100644 (file)
--- a/net/8021q/vlan_netlink.c
+++ b/net/8021q/vlan_netlink.c
@@ -263,10 +263,6 @@ static int vlan_fill_info(struct sk_buff *skb, const struct net_device *dev)
                        for (pm = rcu_dereference_rtnl(vlan->egress_priority_map[i]); pm;
                             pm = rcu_dereference_rtnl(pm->next)) {
                                u16 vlan_qos = READ_ONCE(pm->vlan_qos);
-
-                               if (!vlan_qos)
-                                       continue;
-
                                m.from = pm->priority;
                                m.to   = (vlan_qos >> 13) & 0x7;
                                if (nla_put(skb, IFLA_VLAN_QOS_MAPPING,