Add RCU protection on (struct macvlan_source_entry)->vlan. Whenever macvlan_hash_del_source() is called, we must clear entry->vlan pointer before RCU grace period starts. This allows macvlan_forward_source() to skip over entries queued for freeing. Note that macvlan_dev are already RCU protected, as they are embedded in a standard netdev (netdev_priv(ndev)). Fixes: 79cf79abce71 ("macvlan: add source mode") Reported-by: syzbot+7182fbe91e58602ec1fe@syzkaller.appspotmail.com https://lore.kernel.org/netdev/695fb1e8.050a0220.1c677c.039f.GAE@google.com/T/#u Signed-off-by: Eric Dumazet --- drivers/net/macvlan.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c index 7966545512cfeab3914374675bafa3847e5d7ae1..b4df7e184791d0fe0a60c17522b91b2766847b37 100644 --- a/drivers/net/macvlan.c +++ b/drivers/net/macvlan.c @@ -59,7 +59,7 @@ struct macvlan_port { struct macvlan_source_entry { struct hlist_node hlist; - struct macvlan_dev *vlan; + struct macvlan_dev __rcu *vlan; unsigned char addr[6+2] __aligned(sizeof(u16)); struct rcu_head rcu; }; @@ -146,7 +146,7 @@ static struct macvlan_source_entry *macvlan_hash_lookup_source( hlist_for_each_entry_rcu(entry, h, hlist, lockdep_rtnl_is_held()) { if (ether_addr_equal_64bits(entry->addr, addr) && - entry->vlan == vlan) + rcu_access_pointer(entry->vlan) == vlan) return entry; } return NULL; @@ -168,7 +168,7 @@ static int macvlan_hash_add_source(struct macvlan_dev *vlan, return -ENOMEM; ether_addr_copy(entry->addr, addr); - entry->vlan = vlan; + RCU_INIT_POINTER(entry->vlan, vlan); h = &port->vlan_source_hash[macvlan_eth_hash(addr)]; hlist_add_head_rcu(&entry->hlist, h); vlan->macaddr_count++; @@ -187,6 +187,7 @@ static void macvlan_hash_add(struct macvlan_dev *vlan) static void macvlan_hash_del_source(struct macvlan_source_entry *entry) { + RCU_INIT_POINTER(entry->vlan, NULL); hlist_del_rcu(&entry->hlist); kfree_rcu(entry, rcu); } @@ -390,7 +391,7 @@ static void macvlan_flush_sources(struct macvlan_port *port, int i; hash_for_each_safe(port->vlan_source_hash, i, next, entry, hlist) - if (entry->vlan == vlan) + if (rcu_access_pointer(entry->vlan) == vlan) macvlan_hash_del_source(entry); vlan->macaddr_count = 0; @@ -433,9 +434,14 @@ static bool macvlan_forward_source(struct sk_buff *skb, hlist_for_each_entry_rcu(entry, h, hlist) { if (ether_addr_equal_64bits(entry->addr, addr)) { - if (entry->vlan->flags & MACVLAN_FLAG_NODST) + struct macvlan_dev *vlan = rcu_dereference(entry->vlan); + + if (!vlan) + continue; + + if (vlan->flags & MACVLAN_FLAG_NODST) consume = true; - macvlan_forward_source_one(skb, entry->vlan); + macvlan_forward_source_one(skb, vlan); } } @@ -1680,7 +1686,7 @@ static int macvlan_fill_info_macaddr(struct sk_buff *skb, struct macvlan_source_entry *entry; hlist_for_each_entry_rcu(entry, h, hlist, lockdep_rtnl_is_held()) { - if (entry->vlan != vlan) + if (rcu_access_pointer(entry->vlan) != vlan) continue; if (nla_put(skb, IFLA_MACVLAN_MACADDR, ETH_ALEN, entry->addr)) return 1; -- 2.52.0.351.gbe84eed79e-goog