lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

net: add a recursion limit in xmit path

Browse Source 
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>
This commit is contained in:
Eric Dumazet
2010-09-29 13:23:09 -07:00
committed by David S. Miller
parent ab79ad14a2
commit 745e20f1b6
1 changed files with 11 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
net/core/dev.c
View File

@@ -2177,6 +2177,9 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
return rc; return rc;
} }
static DEFINE_PER_CPU(int, xmit_recursion);
#define RECURSION_LIMIT 3
/** /**
* dev_queue_xmit - transmit a buffer * dev_queue_xmit - transmit a buffer
* @skb: buffer to transmit * @skb: buffer to transmit
@@ -2242,10 +2245,15 @@ int dev_queue_xmit(struct sk_buff *skb)
if (txq->xmit_lock_owner != cpu) { if (txq->xmit_lock_owner != cpu) {
if (__this_cpu_read(xmit_recursion) > RECURSION_LIMIT)
goto recursion_alert;
HARD_TX_LOCK(dev, txq, cpu); HARD_TX_LOCK(dev, txq, cpu);
if (!netif_tx_queue_stopped(txq)) { if (!netif_tx_queue_stopped(txq)) {
__this_cpu_inc(xmit_recursion);
rc = dev_hard_start_xmit(skb, dev, txq); rc = dev_hard_start_xmit(skb, dev, txq);
__this_cpu_dec(xmit_recursion);
if (dev_xmit_complete(rc)) { if (dev_xmit_complete(rc)) {
HARD_TX_UNLOCK(dev, txq); HARD_TX_UNLOCK(dev, txq);
goto out; goto out;
@@ -2257,7 +2265,9 @@ int dev_queue_xmit(struct sk_buff *skb)
"queue packet!\n", dev->name); "queue packet!\n", dev->name);
} else { } else {
/* Recursion is detected! It is possible, /* Recursion is detected! It is possible,
* unfortunately */ * unfortunately
*/
recursion_alert:
if (net_ratelimit()) if (net_ratelimit())
printk(KERN_CRIT "Dead loop on virtual device " printk(KERN_CRIT "Dead loop on virtual device "
"%s, fix it urgently!\n", dev->name); "%s, fix it urgently!\n", dev->name);