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net: add a recursion limit in xmit path
As tunnel devices are going to be lockless, we need to make sure a misconfigured machine wont enter an infinite loop. Add a percpu variable, and limit to three the number of stacked xmits. Reported-by: Jesse Gross <jesse@nicira.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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1 changed files with 11 additions and 1 deletions
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@ -2177,6 +2177,9 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
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return rc;
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}
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static DEFINE_PER_CPU(int, xmit_recursion);
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#define RECURSION_LIMIT 3
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/**
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* dev_queue_xmit - transmit a buffer
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* @skb: buffer to transmit
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@ -2242,10 +2245,15 @@ int dev_queue_xmit(struct sk_buff *skb)
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if (txq->xmit_lock_owner != cpu) {
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if (__this_cpu_read(xmit_recursion) > RECURSION_LIMIT)
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goto recursion_alert;
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HARD_TX_LOCK(dev, txq, cpu);
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if (!netif_tx_queue_stopped(txq)) {
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__this_cpu_inc(xmit_recursion);
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rc = dev_hard_start_xmit(skb, dev, txq);
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__this_cpu_dec(xmit_recursion);
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if (dev_xmit_complete(rc)) {
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HARD_TX_UNLOCK(dev, txq);
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goto out;
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@ -2257,7 +2265,9 @@ int dev_queue_xmit(struct sk_buff *skb)
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"queue packet!\n", dev->name);
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} else {
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/* Recursion is detected! It is possible,
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* unfortunately */
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* unfortunately
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*/
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recursion_alert:
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if (net_ratelimit())
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printk(KERN_CRIT "Dead loop on virtual device "
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"%s, fix it urgently!\n", dev->name);
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