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authorKoki Sanagi <sanagi.koki@jp.fujitsu.com>2011-05-30 21:48:34 +0000
committerDavid S. Miller <davem@davemloft.net>2011-06-02 14:06:31 -0700
commitec764bf083a6ff396234351b51fd236f53c903bf (patch)
tree30c0f8232fe10c76651114dea999b93fa2c8ade5 /net
parent2e4ceec4edaef6e903422792de4f7f37de98cec6 (diff)
net: tracepoint of net_dev_xmit sees freed skb and causes panic
Because there is a possibility that skb is kfree_skb()ed and zero cleared after ndo_start_xmit, we should not see the contents of skb like skb->len and skb->dev->name after ndo_start_xmit. But trace_net_dev_xmit does that and causes panic by NULL pointer dereference. This patch fixes trace_net_dev_xmit not to see the contents of skb directly. If you want to reproduce this panic, 1. Get tracepoint of net_dev_xmit on 2. Create 2 guests on KVM 2. Make 2 guests use virtio_net 4. Execute netperf from one to another for a long time as a network burden 5. host will panic(It takes about 30 minutes) Signed-off-by: Koki Sanagi <sanagi.koki@jp.fujitsu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/dev.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index c7e305d13b71..939307891e71 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2096,6 +2096,7 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
{
const struct net_device_ops *ops = dev->netdev_ops;
int rc = NETDEV_TX_OK;
+ unsigned int skb_len;
if (likely(!skb->next)) {
u32 features;
@@ -2146,8 +2147,9 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
}
}
+ skb_len = skb->len;
rc = ops->ndo_start_xmit(skb, dev);
- trace_net_dev_xmit(skb, rc);
+ trace_net_dev_xmit(skb, rc, dev, skb_len);
if (rc == NETDEV_TX_OK)
txq_trans_update(txq);
return rc;
@@ -2167,8 +2169,9 @@ gso:
if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
skb_dst_drop(nskb);
+ skb_len = nskb->len;
rc = ops->ndo_start_xmit(nskb, dev);
- trace_net_dev_xmit(nskb, rc);
+ trace_net_dev_xmit(nskb, rc, dev, skb_len);
if (unlikely(rc != NETDEV_TX_OK)) {
if (rc & ~NETDEV_TX_MASK)
goto out_kfree_gso_skb;