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net: call rcu_read_lock early in process_backlog
Incoming packet should be either in backlog queue or
in RCU read-side section. Otherwise, the final sequence of
flush_backlog() and synchronize_net() may miss packets
that can run without device reference:
CPU 1 CPU 2
skb->dev: no reference
process_backlog:__skb_dequeue
process_backlog:local_irq_enable
on_each_cpu for
flush_backlog => IPI(hardirq): flush_backlog
- packet not found in backlog
CPU delayed ...
synchronize_net
- no ongoing RCU
read-side sections
netdev_run_todo,
rcu_barrier: no
ongoing callbacks
__netif_receive_skb_core:rcu_read_lock
- too late
free dev
process packet for freed dev
Fixes: 6e583ce524
("net: eliminate refcounting in backlog queue")
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
e9e4dd3267
commit
2c17d27c36
1 changed files with 16 additions and 16 deletions
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@ -3774,8 +3774,6 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
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pt_prev = NULL;
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rcu_read_lock();
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another_round:
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skb->skb_iif = skb->dev->ifindex;
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@ -3785,7 +3783,7 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
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skb->protocol == cpu_to_be16(ETH_P_8021AD)) {
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skb = skb_vlan_untag(skb);
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if (unlikely(!skb))
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goto unlock;
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goto out;
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}
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#ifdef CONFIG_NET_CLS_ACT
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@ -3815,10 +3813,10 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
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if (static_key_false(&ingress_needed)) {
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skb = handle_ing(skb, &pt_prev, &ret, orig_dev);
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if (!skb)
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goto unlock;
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goto out;
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if (nf_ingress(skb, &pt_prev, &ret, orig_dev) < 0)
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goto unlock;
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goto out;
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}
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#endif
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#ifdef CONFIG_NET_CLS_ACT
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@ -3836,7 +3834,7 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
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if (vlan_do_receive(&skb))
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goto another_round;
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else if (unlikely(!skb))
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goto unlock;
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goto out;
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}
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rx_handler = rcu_dereference(skb->dev->rx_handler);
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@ -3848,7 +3846,7 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
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switch (rx_handler(&skb)) {
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case RX_HANDLER_CONSUMED:
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ret = NET_RX_SUCCESS;
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goto unlock;
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goto out;
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case RX_HANDLER_ANOTHER:
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goto another_round;
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case RX_HANDLER_EXACT:
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@ -3902,8 +3900,7 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
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ret = NET_RX_DROP;
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}
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unlock:
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rcu_read_unlock();
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out:
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return ret;
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}
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@ -3934,29 +3931,30 @@ static int __netif_receive_skb(struct sk_buff *skb)
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static int netif_receive_skb_internal(struct sk_buff *skb)
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{
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int ret;
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net_timestamp_check(netdev_tstamp_prequeue, skb);
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if (skb_defer_rx_timestamp(skb))
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return NET_RX_SUCCESS;
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rcu_read_lock();
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#ifdef CONFIG_RPS
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if (static_key_false(&rps_needed)) {
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struct rps_dev_flow voidflow, *rflow = &voidflow;
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int cpu, ret;
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rcu_read_lock();
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cpu = get_rps_cpu(skb->dev, skb, &rflow);
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int cpu = get_rps_cpu(skb->dev, skb, &rflow);
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if (cpu >= 0) {
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ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
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rcu_read_unlock();
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return ret;
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}
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rcu_read_unlock();
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}
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#endif
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return __netif_receive_skb(skb);
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ret = __netif_receive_skb(skb);
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rcu_read_unlock();
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return ret;
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}
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/**
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@ -4501,8 +4499,10 @@ static int process_backlog(struct napi_struct *napi, int quota)
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struct sk_buff *skb;
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while ((skb = __skb_dequeue(&sd->process_queue))) {
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rcu_read_lock();
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local_irq_enable();
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__netif_receive_skb(skb);
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rcu_read_unlock();
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local_irq_disable();
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input_queue_head_incr(sd);
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if (++work >= quota) {
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